I'm sure this has been asked before... but who [was] Culwyeh? From the quote about his/her/its name being forgotten to all but the most devoted pupils of necromancy, one might inferr that Culwyeh was a necromancer of signifigant power - or perhaps some dark and forgotten god?
Which leads one to wonder... was Bhal'al the first necromancer, or did he simply [recover] the dream of unlife, lost since time immemorial but once possessed by sorcerous entities even older than himself?
Anyway, the wights were once called "messengers of Culwyeh" which, to me, suggests that either Culwyeh invented them, or they were created in his/her/its honor...