That permanently hides the attack button, blooddancer.
The solution:
Go to the object editor, to your unit's attacks. make the unit use none of its 2 attacks (the unit will no longer have the attack button visible and can't attack).
Next, go to your item and add an orb ability to it. Such and orb ability is the abilities found at the "Orb of Lightning" item. This ability unlocks either attack 1 or attack 2, allowing your unit to use that attack once he gets the item.