[@TheHangedMan]
Well, i'm stretching the definition of "weapon" a bit here. My reasoning goes like that: first, "weapon" could be defined as an "external object that helps its user in the fight", since you can have gloves or armour as one IIRC; second, there are warrior cultures that use tattoos and bodypaint to help them with that - usually laced with chemicals that inure users to pain or put them into battle frenzy, or used for intimidation purposes. Now, you could argue that tattoos are not really "external", but well, ink for them was, at some point, and if something like implanted claws would count, I don't see why tattoos should not.