Occasionally (albeit incorrectly) thought to be the weapon used by Cain to slay his brother Abel. A quick look at Genesis 4 specifies no murder weapon, merely that Cain
rose up against Abel his brother, and slew him.
The jawbone of an
ass does actually show up as a
weapon in
Judges 15, employed by
Samson to slay a thousand men of unspecified nationality, presumably
Philistines from the passages before.