Both a sophisticated and ultimately disposable piece of spycraft, and the name of the profession of the people who use them.
A class of cybernetic prosthetics worn over the face
A strange mask containing a merciless demon, a parasite on those around it.
A possible answer to what happens to spells when a mage dies. If the spell is strong enough, say and enchantment or other permenant effect, part of the mages spirit may become lodged in the magic. It may be a way for items to gain some kind of intelligence, but a mage who has knowledge of this fact would be very hesitant about enchanting anyone or thing. He might have other plans for his afterlife than counting the change in your bag of holding.
Preists, I think, would have this sort of thing covered.