A two-handed scythe made from the fang of a large creature whose venom causes petrification. Finally get to turn my least favorite attack (Medusa Gaze) back at his enemies.
Even better, only the portion of flesh slashed is petrified, so he can take his time deciding how to complete the kill while portions of the victim are still aware and writhing. Petrify a man's lower portion from the waist down, break off his stone legs to make him lighter and carry him off somewhere. Petrify just the head and watch the body freak out.