Diablo 3 Weapon Science Guide
Diablo 3 Weapon Science Guide submitted by fgr.
In Diablo 3, your damage is entirely dependent on the weapon you're holding. A lot of people have been asking about whether to use 2H or Dual Wield, and what type of weapon works best with their spells. I did some experiments to figure this out, and I present those results below:
Some people have claimed Diablo 3 only uses your DPS to calculate skill damage. That is false.
I compared a very quick dagger to a slow 2H hammer with nearly the same DPS. Despite having the same DPS, spells like Arcane Orb did a lot more damage per cast with the hammer.
I used a dagger (46.5 dps, 16-46 dmg * 1.5 attacks/sec) and a 2h hammer (46.35 dps, 47-56 dmg * 0.9 attacks/sec).
I tried a variety of spells, including Blizzard, Arcane Orb, and Ray of Frost. (10 full casts of Blizzard per weapon, measured before/after enemy HP values with the HP overlay.)
With the 2h hammer, my Blizzards did an average of 590.7 damage.
With the dagger, my Blizzards did an average of 346.3 damage.
(Deviation was small, this is definitely not a statistical fluke. Note the ~1.706x experimentally measured factor corresponds within 3% to the ~1.661x ratio you'd predict by comparing the weapons' individual average per-hit values.)
Arcane Orb did more damage per cast with the hammer. Not sometimes; every time. I also tried with/without ~+30% IAS. The +%Attack Speed gear made no difference on the damage per orb.
However, IAS did affect the average damage per tick on Ray of Frost.
Conclusion: Technically speaking, you do the same average DPS on Arcane Orb with the dagger or the hammer, but only as long as you're chain-casting it. Because the spell is expensive, you can only afford to cast it ~3 times in a row, and the total damage of those 3 casts will be much higher with the hammer. However, the casting animation will be slower.
Note: I did no experiments on cooldown skills. It is possible that cooldown damage uses DPS instead of raw damage. I have no data on this at present.
Some skills will work better with fast weapons, some will work better with hard-hitting slow weapons. If you are favoring a skill that does something special each time you cast it (like Attunement, which adds 4 arcane power on every cast, or a Fury Generator), then a quick dagger will work best. If you are favoring an expensive spell, like Arcane Orb (or a Fury Spender), then you want as much punch as possible per use, and you should focus on max damage-per-hit.
It can be a lot easier to get your DPS up by acquiring +%Attack Speed gear, but this won't affect your damage at all on skills like Arcane Orb! However, fast attacks enjoy better granularity, rather than wasting DPS on overkill, so if you don't need the extra punch of a slow weapon, you should look for speed.