About the Nortis - I did not get, why this corrupted weapon is usable for thralls, meanwhile Carnage sword is not (they won’t do any damage with it at all).

Yes, I have few from each I guess. Mithra’s justice for example, then there is the Wyrd which sucks, Aja’s bane being good only for PvP purposes maybe, cause there are maces with far higher dmg.