So there's an anime character in A Certain Magical Index named Touma. His Furious Hidden Inner Power is the ability to break magic attacks with a punch, and shatter all armor. So what if there's a set of knuckledusters which let you do that? Design as a Claw class weapon, shame them like brass knuckles and give them resistance to slow, knockback resistance, willpower boost, mana generation, minor healing, say 5 points a second, and reduce armor 94 points a hit. I was also thinking you might be able to pop up a shield 3% chance on being struck like the engineers have, and offer 90% chance to disrupt attack like with a mace/hammer class weapon. That would allow anyone equipping this weapon to duplicate many of Touma's punching abilities.
Naturally you either offer upgrades to the thing based on use, or you offer drops of stronger versions through the game so it doesn't become too weak to use.