Dual wield

Dual wield allows the character to hold a weapon in each hand (main hand and off hand). The character can deal some damage with the weapon in the off-hand between strikes with the strong hand. This is a very important passive ability as it allows a character to deal significantly more damage as compared to a single one-handed weapon. Once it is acquired, the character will immediately begin to strike with each hand (if there is a weapon in each) while in battle.

Warriors, hunters, rogues, death knights and shamans are able to dual wield weapons, however there are some limitations:
 * Warriors and shamans have to choose Fury and Enhancement respectively in order to dual wield.
 * Death knights, rogues and hunters are able to dual wield weapons when created.

A weapon equipped in the main hand will deal full damage, while an off-hand weapon will deal 50% of its damage. Death knights have the talent Nerves of Cold Steel, which increases hit chance and offhand weapon damage.

Most disarm debuffs do NOT affect off-hand weapons. While abilities that require a weapon in the main hand can't be used, the off-hand weapon will still deal its regular damage. Rogue disarm removes both main-hand and off-hand equipment.

Miss chance
Dual wielding adds a 19% miss penalty to both main and offhand weapons. The base miss rate for all characters is 5%, so each weapon by itself has a 24% chance to miss (19% + 5%). The talents Precision for rogues and warriors, and Nerves of Cold Steel for death knights increase the chance to hit with both weapons while dual wielding. For each point the attacker’s weapon skill exceeds the target's defense skill, the miss chance decreases by 0.04%. For each point a target’s defense skill exceeds his opponent’s weapon skill, the miss chance increases by 0.04%.

Important note: Prior to version 1.8, dual wield's miss chance had a hard cap of 19%, meaning that all dual-wield auto-attacks had a minimum 19% miss chance regardless of how much +hit% gear was equipped. In version 1.8, this hard cap was removed. The exact wording of the 1.8 patch note was:


 * "Items which provide +hit chance will now be allowed to counteract the increased miss chance penalty of dual-wielding."

Take a level 80 rogue for example vs. a level 83 raid boss: the rogue has 5% + (0.04% * 15) = 5.6% base miss chance (assuming the boss has no Defense skill bonuses), plus 19% dual wield miss chance, leaving us with a total miss chance of 24.6%.

Note that the +19% miss chance for dual-wielding only applies to ordinary auto-attack melee attacks. It does not apply to any special attack powers that cost rage, energy, or mana -- instant attacks such as Sinister Strike, Stormstrike or Heroic Strike incur the dual wield miss penalty. So, with 9% +hit from gear/talents a dual-wielder will never miss with an instant attack (although the attack can still be dodged, parried, or blocked -- see the Attack table article). However, a dual-wielder would need 25% +hit if he wants to remove the miss chance for auto-attack/white damage totally.

Chance on hit proc rate
Some weapons have special abilities that will go off (or "proc") on some hits. These abilities are preceded in the weapon's description by the words "Chance on hit:".

The chance for one of these abilities to go off on a successful auto-attack strike are independent of whether the weapon is being wielded in the main hand or wielded in the off hand. However, these abilities also have the same per-strike chance to go off when making an instant attack (such as Sinister Strike, Mongoose Bite, Overpower, etc.). Instant attacks are always assumed to be made with the weapon in the main hand only. This means that over the course of a normal fight in which several instant attacks are used, a given weapon's chance-on-hit ability will go off more often if the weapon is wielded in the main hand than if it is being wielded in the off hand. The exception to this is the shaman Stormstrike ability, the rogue Mutilate ability and the warrior Whirlwind ability, in which all three abilities give an extra instant attack with both wielded weapons.

Proc rate for other weapon abilities
Some weapons have abilities that go off some of the time, but are not listed as "Chance on hit:". For example, the Crusader enchant reads "... often when attacking in melee ...", and the Misplaced Servo Arm's ability reads "Equip: Chance to ...". The proc chances for these kinds of abilities are separate and distinct from the "Chance on hit:" abilities discussed above.

The proc rate for these abilities is generally based on an average rate per minute, not a chance per strike. Whether the proc rate for such an ability on a one-hand weapon is affected by which hand the weapon is wielded in is something that needs to be experimentally verified.

Cataclysm
Fury Warriors and Enhancement Shamans gain the ability to Dual Wield at level 10 when they choose their talent tree. Warriors and Shamans that choose a different tree are no longer able to Dual Wield.