: That's something that was never hinted at in the game.
: Culwyeh is a Celtic name, meaning she was probably a
: Warlock.
Also, perhaps that could explain the "Moagim" reference in Tales. Culwyeh is a very old name, forgotten by all but the most devout students of necromancy. So, perhaps s/he (being reincarnated, Shiver could have been a man in a previous life) was one of Moagim's Fallen Lords, and The Head - being as old as the world - knew about her weakness from way back then, and told Rabican.