Arthur kills witch with Carnwennan

But this man can’t go nowhere without getting into trouble. On the way, Arthur has to stop to fight The Black Hag, a witch that killed a couple of knights with her bare hands, and a few hundred more with magic. Arthur defeats her by THROWING CARNWENNAN AT HER AND CUTTING HER IN HALF, which even he had no idea it could do. Merlin is just there watching and taking notes.

-The 21st Century Guide to Mythology: Arthurian Myths Retold pg 46.