If I have an amulet of mighty fists and some claws, can I enchant the amulet with the keen and/or vorpal weapon special abilities? If so, do they simply not function for somebody who wears the amulet who doesn't have claws or a similar slashing/piercing natural weapon?
If this works, which I assume it would, can I use the keen/vorpal amulet in conjunction with my unarmed strike via use of boar style to deal slashing damage?