The physics of Brass knuckles? Reading Terry Pratchett's 'Night Watch' got me wondering: How do knuckle dusters work? I mean in terms of the basic 'force= mass*acceleration' sort of equations. Does the metal provide a smaller point of contact then ordinary knuckles? Does the rigidity of the metal prevent some of the force of the impact being absorbed by the user's joint structure? Maybe they also give a confidence boost to the user?