The Forbidden Weaponsare a special type of weapons that could only be used once and would become rubbish after or simply disintegrate. A few could be used several times but there was still a limit.
Despite this limitation, Forbidden Weapons are much more powerful than conventional weapons and easier to use. For example, an Immortal Emperor True Treasure requires a mighty Blood Energy to empower it. One is not be able to unleash an invincible blow without enough strength. However, this is not the case for a Forbidden Weapon. It does not matter whether the user is a Godking or a Mortal, they can still use the strongest blow of a Forbidden Weapon.