As used in this part, “metal knuckles” means any device or instrument made wholly or partially of metal that is worn for purposes of offense or defense in or on the hand and that either protects the wearer’s hand while striking a blow or increases the force of impact from the blow or injury to the individual receiving the blow. The metal contained in the device may help support the hand or fist, provide a shield to protect it, or consist of projections or studs

which would contact the individual receiving a blow.