To use this command, you must have trained the skill "Weaponsmithing"
Hold a weapon in your right hand, it must not already be Temporarily Enchanted, type "balanceweapon"
This will increase chance to hit and damage output of the weapon.
Duration and Intensity are dependant on your level of the Weaponsmithing skill.
Melee fighters should have their weapon balanced at all times. It can significantly increase damage and for some skilled classes allow for an extra Multiple Attack.