Q:

Can an Amulet of Mighty Fists have restricted special abilities?

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?

A:

Keen or vorpal: Yes.
Keen and vorpal: No, because AoMFs have a +5 enchant limit.
Yes, they'd only work if the weapon at hand was slashing, its slashiness coming from claws or boar style should be fine.

