Arioch is the name of an unaligned god that plays a very minor role in NetHack.
The name originally appears in the Bible within the Book of Genesis as the name of the "King of Ellasar", who participated in the Battle of the Vale of Siddim. In the Elric series by English author Michael Moorcock, Arioch is the Chaos Lord served by the family line of Elric of Melniboné, the wielder of Stormbringer, which is why the title and weapon are both granted upon crowning a chaotic character.
Arioch, the patron demon of Elric's ancestors; one of the most
powerful of all the Dukes of Hell, who was called Knight of
the Swords, Lord of the Seven Darks, Lord of the Higher Hell
and many more names besides.