Dual wielding is a feature confirmed to be released with the Evolution of Combat.
The feature consists of wielding two weapons, a regular version of the weapon in the main weapon hand, and an offhand version of the weapon, in the shield hand. Dual wielding will increase the damage output of the player, at the cost of sacrificing defensive and life points bonuses granted by a shield.
There will be specific abilities unlocked if dual-wielding two of the same weapon class (ranged, magic or melee). If two different classes of weapon are being wielded, then the abilities available will be determined by the main hand weapon.