Shroudsight

An adept of spirit eventually learns to see past the thin veils separating our world from the spirit realm, developing an ability known as shroudsight. This extra sense becomes innate, requiring no special focus to activate -- with it, the mage will simply see denizens of and travelers through the astral plane. This sight allows her to see the shades, phantoms, wraiths and ghosts of the spirit realm, as well as astrally projected or voidwalking souls. This second sight furthermore permits the scholar to recognize demonic possessions and demon-bound weapons for what they are. Many wizened old magi have warned their apprentices about this ability, for once the eyes opened, that which is Seen cannot be Unseen.