The most important part of playing a Retribution Paladin is picking the right tool to bash things good with. You could be wearing all epics and be buffed from here to Silithus, but if you're wielding [The Stoppable Force], you're not going to do much more than tickle your target. Picking a weapon for an Alliance Retribution Paladin is not as simple as grabbing the meanest looking hammer or axe you can find and proceeding to the hack 'n slash phase. A little consideration for the Paladin combat mechanics can boost your damage up by a noticeable amount.
First and foremost is the weapon's DPS average. That's the number denoted in parentheses on the tooltip - for our Stoppable Force above, it's 31.0 damage per second. What this number tells you is that if you were to just pick up the hammer and start whacking away with no stats, no buffs, and just auto-attacked a same-level target for a good 60 seconds, you'd probably cause 1860 damage. This says nothing about the size of each hit, the frequency of the damage, or anything else. All it tells you is that you can cause X damage every second of continuous use without using skills, stats, or abilities. Next, note the weapon's damage range, which for the Stoppable Force is 89-134. The damage range tells you how much each attack you make with the weapon should hit for before stats, abilities, and skills come into play. So, if you were to whack a same-level dude with our Stoppable Force just once, and had no stat-boosting armor on, you'd most likely deal something of the order of 100ish damage, or somewhere in between our two damage range caps of 89 and 134.
"But wait a second, how does a hammer that can smack my target for over 100 damage almost every time end up only doing an average of 31 damage per second?" This is where our 3rd factor comes in: weapon speed. Weapon speed determines how often you can swing your hammer of smash-face or sword of slice'n'kill. For the Stoppable Force, weapon speed is 3.6, meaning if you turned on auto-attack and walked away, you'd attack once every 3.6 seconds continually until either the target dies, you die, or the target wanders away out of boredom. Take those big big hammer blows of 89 to 134 and space them out over 3-4 seconds each, and you'll find that the damage is about 31 per second, or about 112 every 3.6 seconds (right in the middle of our weapon's damage range). Now that you have a basic understanding of the stats on melee weapons and how they interact with each other, I can go a little deeper into the conversation!
For Alliance Retribution Paladins, one seal is the damage seal. It's often referred to as "Seal of Casino," "Seal of Chance," and other such endearing and luck-based terms. Blizzard dubbed it Seal of Command. Don't ask me why, 'cuz I don't feel like I command anything when I use it - I'm at the mercy of dice rolls. The ability description from Wowwiki:
Gives the Paladin a chance to deal additional Holy damage equal to 70% of the damage of the attack. Only one Seal can be active on the Paladin at any one time. Lasts 30 sec.It does damage when it's judged based on a number of factors, but the Judgment of this seal is not what we're concerned with right now since it's not affected by our weapon at all. Judgment of Command will do the same damage whether you are using a [Torch of the Damned] or a [Kobold Mining Shovel]. It is the seal's power we are concerned with here. Read carefully - 70% of the damage of the attack. This means that if your attack is large, the seal will also be large. Consequently, if your attacks are smaller, the seal will be small. The chance for the seal to do damage stays constant no matter how big, small, fast, slow, or cute your attacks are: if you continually attack, you'll see an average of 7-8 Seal of Command procs per minute. Using our Stoppable Force as an example, Seal of Command would do damage every 2nd or 3rd attack, and the damage would be in the order of 60-95ish. That's a hefty damage increase. Add in the fact that it counts as Holy damage and therefore can't be reduced by armor, and you've got a real potent punch.
One thing to notice though is how the weapon's damage range affects your Seal of Command damage. Let's take our Stoppable Force, keep the weapon DPS the same but tinker with its other stats. If you were to take that hammer and drop it to 1.0 speed, the average of the damage range would drop to 31-ish, as you'd be making an attack every second, generating a true 31.0 DPS. No matter whether you attack once every second or once every four seconds, you will see the same number of Seal of Command procs over any length of time. So, attacking with our 1.0 speed 31 DPS weapon, you'd see seal procs of about 22 damage. That's a far cry from our 60-95 when using the 3.6 speed 31 DPS hammer! This is what you must note about Retribution weapons - size matters. Whenever possible, you want to reach for the biggest, heaviest, slowest, most face-smashiest weapon possible, because if two weapons have the same DPS and different speeds, the slower one will have the higher damage range per attack, and that's what your seal's damage is calculated from. When your weapon has a high top-end on its damage range, your Seal of Command has a high top-end to its damage range.
Now, don't go out and use that 20 DPS 3.8 speed mace you found forever just because it's big and slow. Weapon DPS still factors in. A 90 DPS two-handed weapon that's 3.0 speed will have a higher damage-range than a 60 DPS two-handed weapon with 4.0 speed. You're better off with the faster one in that case. And you can't discount the auto-attack damage you cause and choose a weapon based solely on how big your Seal of Command would be with it. BUT, if you're presented with two fairly equal weapons in terms of DPS on the weapon, snag the one with the higher top-damage, which generally comes with a slower attack speed.