Isuka asked about this last night as Brendore was in the raid, so I thought I'd organize my thoughts a bit in a forum post. This is going to be very long, so I'll toss a quick summary at the front.
* Special abilities very heavily scaled to weapon speed - the slower the better.
* DPS is comparable to an Arms Warrior, and uses most of the same gear. Overall, AP and crit are superior to spell damage.
* Reliant on mana rather than rage, and has difficulty sustaining maximum DPS without going OOM.
* Can maintain the Judgements of other Paladins on mobs, meaning you can get lots of uptime on Light or Wisdom without risking your Holy Paladins in melee range.
* Improved Sanctity Aura increases party damage by 2%.
* Sanctified Crusader increases critical strike chance by 3% on mobs with Judgement of the Crusader.
* Highly reliant on procs and crits for DPS.
* No inherent threat reduction without sacrificing DPS buffs or needing multiple Paladins.
* Has a 6-second incapacitate on Humanoid targets in addition to a 6-second stun, every minute.
* Has enormous synergy with a Protection Paladin tank.
* Can't heal worth a damn.
Often overlooked, the choice of weapon defines the Retribution Paladin every bit as much as any other melee DPS class, if not more. What you want is simply the slowest weapon possible. In this case, top-end damage is even more important than base DPS - a 100 DPS weapon with a 2.8 speed is inferior statistically to a 90 DPS weapon with 3.8 speed. See Seal of Command for more info.
Think Arms Warrior here. Ignore the Blizzard pundits claiming that spell damage is vital to a Retribution Paladin. The small coefficient that Seal/Judgement of Command and Crusader Strike get is not as important as melee attack power and melee crit. If otherwise desirable Retribution gear has spell damage on it, go for it! But don't pass up on a beautiful Str/Agi/Sta piece because it doesn't have spell damage.
The one problem stat-wise is that you need mana to do damage, and that base 4K pool at level 70 just won't cut it for long fights. In this respect, Retribution Paladins are victims of stat dilution just as much if not more than Enhancement Shamans.
So, in order, you want to emphasize:
* Strength - Get this over pure attack power, because AP = 2x Strength, and you get a 10% bonus from Divine Strength (you did get that talent, right), not to mention 10% more from Kings if it's available.
* Attack Power - See above. You prefer Strength, but AP is good too.
* Agility/Melee Crit - Yes, you need crit. Paladins' Agi/Crit ratio is very favorable here compared to Rogues or Hunters, plus you get some Dodge out of it in the event you need not to get hit by something. There's no compelling reason to prefer one over the other.
* Intellect - You need mana to DPS, and unlike the Tankadin, you won't be getting tons of it from being healed. Stock up on mana pots (Fel Mana is great here because you don't depend on spell damage as much as other mana users).
* Spell Damage - Okay, so I said it's not vital. It's still very nice to have - your Judgements will thank you, as will Exorcism and Holy Wrath against those tasty Undead/Demon opponents. Crusader Strike and Seal of Command get improved as well, but as I said before, AP gives you more bang for the buck.
* Mana per 5 seconds - This is marginally useful for Retribution Paladins - it becomes a heck of a lot better if you are the only Paladin and don't maintain Judgement of Wisdom on your targets. Otherwise, it's skippable.
* Stamina - Dead Retribution Paladins do no DPS. This applies to all classes, so it almost goes without saying.
* Melee hit rating - Good for boss encounters, but the ideal raid DPS spec will also grab Precision from the Protection tree, saving you from having to stack up too much hit rating.
* Spell hit/crit - 4 of a Retadin's primary damage abilities are melee/ranged, not spells, so spell hit/crit gives much less utility. It does affect your damage-dealing Judgements, Exorcism, Holy Wrath, and even Righteous Defense (in the event you need to taunt some mobs that are beating on squishies).
I'm not going to cover all Ret talents here; just the ones that I find most applicable to a raid setting and a Paladin's DPS role.
* Improved Blessing of Might - Hunters and melee DPS love this talent. Nuff said. It's far better than Kings for raw DPS, except possibly for Survival Hunters.
* Improved Seal of the Crusader - For 3 points, you get a modest increase to DPS on mobs you judge with Crusader. The benefit of this over Benediction is arguable, but it makes good filler to get you to the next tier. It also buffs Protadins if you run with them.
* Pursuit of Justice - skip it; a meta gem is just as good.
* Seal of Command - This the core Retribution DPS ability. Overall, this talent can account for 30% or more of a Paladin's DPS. I'll discuss it more under combat mechanics.
* Vindication - This is much more of a PvP talent than PvE; a 15% reduction to Strength and Agility makes very little difference to boss DPS.
* Eye for an Eye - Since mob spells don't crit, this is absolutely worthless to a PvE Paladin.
* Sanctity Aura/Improved Sanctity Aura - The base talent is only so-so for raid DPS because it only benefits the Paladin himself (not that a 10% increase in Holy damage is bad). The improved version buffs the party's DPS by a flat 2%, making it very nice for the melee group to have (and even making it worthwhile to put the Retadin in a caster group if there's no other option). If there is a Paladin tank, however, this talent can effectively increase his threat generation by 12%, which is huge.
* Vengeance - This talent is where the Paladin's DPS starts scaling up. For 5 points, each time you crit, you get a stacking buff that improves all damage by 5% for 15 seconds. It stacks up to 3 times. It's basically identical to Flurry.
* Sanctified Judgement - A good mana conservation talent, this gives you back half the cost of your Seals when you Judge a target.
* Sanctified Crusader - Improves the critical strike chance of all attacks made against the judged target by 3%. This, combined with Improved Sanctity Aura, is where the Retribution Paladin really starts to benefit the raid as a whole, particularly a melee-heavy raid.
* Repentance - A six second incapacitate on a Humanoid target every minute. It's a great way to save squishies from messy death if the mob in question can be CC'd. It's much more of a PvP talent, but for 1 point it's hard to pass up.
* Crusader Strike - This talent is the reason Retribution Paladins can raid at all. Deals weapon damage + 40% of Holy spell damage as Holy damage with a 10 second cooldown, and refreshes the duration of all Judgements on the target. Just like Command, it scales with the base damage of your weapon.
The combat mechanics
Okay, now that we've discussed talents, let's look at how a Retribution Paladin does his damage. Looking at a recent Recount listing my top 3 damage abilities, the results looked roughly as follows:
White damage: 50%
Seal of Command: 20%
Crusader Strike: 20%
The extra 10% comes from Exorcism, Holy Wrath, Judgements, and the various other things that I can do. Digging a bit deeper, we see that, while DPS is obviously key, the Paladin's core damage abilities are based not on DPS per se, but on base weapon damage and attack speed.
* Seal of Command has a chance to deal 70% of weapon damage as Holy damage, plus a very modest spell damage coefficient. It procs 7 times per minute on average.
* Crusader Strike deals weapon damage + 40% of Holy spell damage as Holy damage. It is on a 10 second cooldown (roughly 6 PPM if used every time it's available). Its other, less well-known property is that it refreshes the duration of all Judgements on the target, not just those cast by the Paladin himself, making it ideal when grouped with another Paladin who can Judge Wisdom or Light (or even both, if you have enough pallies).
As should be obvious, the slower the weapon the Paladin uses, the better his Holy damage output, period. Assuming zero spell damage (not unreasonable - my current gear set has zero), the formulas are roughly as follows:
* SoC: Chance to proc = [Weapon Speed] * 7 / 60; DPS = [Weapon Damage] * 0.7 * [Chance to proc]
- On a 3.0 speed weapon, this adds 24.5% to base DPS as Holy damage.
- On a 3.5 speed weapon, this adds 28.6% to base DPS as Holy damage.
- On a 3.8 speed weapon, this adds 31% to base DPS as Holy damage.
* Crusader Strike: DPS = [Weapon Damage] * 6 / 60.
- On a 3.0 speed weapon, this adds 30%.
- On a 3.5 speed weapon, this adds 35%.
- On a 3.8 speed weapon, this adds 38%.
I believe that Crusader Strike may be affected by attack speed normalization, meaning that AP gives a flat benefit rather than scaling with weapon speed. If that's the case, then the above statistics will be slightly off.
It's also important to remember that, unlike white damage, Holy damage is not mitigated by armor. Also note that these are best cases, using the abilities whenever they are available. In practice, you'll never achieve 100% efficiency.
* Additional damage is caused by Judgement of Command, but it's relatively small - the most effective time to use it is when the mob is stunned or incapacitated, as JoC does double damage in these situations. JoC scales with spell damage, however, not melee damage, and as most bosses can't be stunned, its main application is as a DPS-booster against trash. It can make a good trigger for Vengeance with the boosted crit chance from Fanaticism.
* Exorcism is an instant-cast nuke on a 12 second cooldown that works only against Undead.
* Consecration is an instant-cast AoE DoT with an 8 second duration and cooldown. Its DPS is relatively low.
* Holy Wrath is a 2 second cast AoE on a 1 minute cooldown that works only against Undead.
These are great situational spells, but with the very low amount of spell damage that Retadins typically use, they are very mana-inefficient.
* Retribution Aura - great for AoE pulls, this ability may add a very small amount of threat to the tank but is otherwise much less helpful to a raid group than Sanctity, or even Devotion or Concentration in applicable situations.
* Hammer of Wrath - As this ability scales with spell damage and interrupts melee swings, it's usually better for a Retribution Paladin to continue his normal DPS cycle rather than stop to cast HoW when the mob hits 20%. This ability is much better for Holy and Protection Paladins.
Other mechanical notes:
* Seal of Command, Crusader Strike, and Hammer of Wrath are all considered melee/ranged attacks and use those mechanics to calculate crit chance and crit damage multipliers.
* Judgement of Command uses melee crit chance and multipliers, but is considered a spell for purposes of hit/miss mechanics.
* Crusader Strike is considered an instant melee attack, not a spell, and is not blocked by silencing effects. All other Paladin abilities are blocked by silence with the exception of Divine Shield.
* Judgement is not on the global cooldown, so you can integrate it with macros and other parts of your combat sequence.
The combat sequence
* Cast Seal of the Crusader before the pull. To maximize mana efficiency, start enough before the pull that you regen the mana spent.
* On the pull, cast Judgement of the Crusader on the target. This starts your melee autoattack, so wait for tank to build initial threat.
* Cast Seal of Command.
* Cast Crusader Strike whenever the cooldown is up (10 sec).
* If the target is Undead/Demon, cast Exorcism whenever the cooldown is up (12 sec). This is mana-intensive.
* For maximum DPS, judge and recast Command whenever the Judgement cooldown is up (8 sec talented). Try to time this so that it doesn't occur during a melee swing or you may miss the chance to proc Seal of Command.
* For maximum sustainability, judge and recast Command whenever the Seal is about to expire (30 sec). This essentially gives you a free Judgement, since 50% of the mana cost of the seal is recouped by the Sanctified Judgement talent.
Tips and tricks:
* For maximum burst DPS, pop Avenging Wrath along with one or both trinkets. If possible, do this while you already have one or more Vengeance procs, as the extra 30% stacks.
* Vengeance is key to maintaining Retribution DPS. If a Vengeance stack is about to expire, judge Command - the high chance for this to crit may refresh the Vengeance.
* Ask your fellow Paladins to Judge targets with Wisdom and/or Light, depending on the raid makeup. You can maintain it with Crusader Strike, and it significantly boosts your own mana longevity as well as the raid's.
Put simply, Retribution Paladins have the second worst threat situation in the game, just behind Enhancement Shaman. In addition to having no inherent threat reduction, we also have no threat dump ability and we are in melee range of the mob, meaning we pull aggro at 110% rather than 130%. Furthermore, the Paladin's reliance on random burst damage means that at some times we'll be tooling along at, say, 200 DPS, only to jump to 1000 or more when we get a string of crits. This can pull aggro off of any tank in short order.
Two things mitigate threat generation. The first is Blessing of Salvation. If a Retribution Paladin is the only Paladin in a raid, he should consider tossing this on himself rather than Might or Kings. If you're with a Holy or Protection Paladin, make sure to get (and maintain) a 5-minute Salvation. The second is Divine Shield. Like Rogues' Vanish, once every 5 minutes a Paladin can drop his threat to zero. Unlike Rogues, when the buff expires, he's right back to the same place he was before. Also unlike Rogues, Avenging Wrath (30% increased damage for 20 seconds every 3 minutes) causes a debuff that prevents Divine Shield from being used for 1 minute, so our DPS booster comes at the very specific expense of being able to do anything if that DPS pulls aggro.
I hope I didn't bore you.
Edit: Fixed a couple of typos.