The Dual-Wield Token is a token item.
When the Dual-Wield Token is in the inventory, another item slot appears to the left of the hotbar. Items placed here can be wielded to create the effect of 1.9 wielding. They cannot be used for their offensive (left-click) purpose, such as attacking, but can be used for interaction (right-click) purposes, such as torch-placing or water-bucketing.
When the Dual-Wield Token is in the inventory, the effect of the offhand slot is increased as well as mouse function changed. It is mainly an attack and mining tool.
Clicks by the mouse will result in an offensive use by the item in its respective slot. This is relative to direction, not to handedness. A left-click results in an attack using the weapon in the left hand, and a right-click results in an attack using the weapon in the right hand. This also applies to mining. For example, a pickaxe and a shovel can be held and used in conjunction.