Crocea Mors (Latin for "yellow Death") was the name given to Julius Caesar's sword, according to the legends presented by Geoffrey of Monmouth. In Middle Welsh versions, it is called Angau Coch ("Red Death") or Angau Glas ("Grey Death").
The British prince Nennius acquired it when, during single combat with Caesar, it got stuck in his shield. It killed everyone Nennius struck with it. Nennius died fifteen days after the battle of a head wound inflicted by Caesar, and the sword was buried with him.
It has also received reference within modern popular culture, the web-series RWBY, being the weapon of the secondary character Jaune Arc.
References
Crocea Mors Wikipedia(Text) CC BY-SA