I wonder if it would really be that hard to make it not be armor dependent?
I mean, worst that happens, is the +4 Prot gets added to the Base Prot, so that it affects both Body and Head (I may be crazy, but I'm assuming that's why it's added to armor, so that helmets get it as well...).
I know the math with Base Prot + Armor Prot is a little wonky, so it may not make everyone happy to change it that way..... But it may be better than being able to get +16 Prot on a unit with 3 misc slots.