Excalibur

Scabbard
The scabbard of Excalibur is considered far more valuable than the actual sword because whoever possesses the scabbard cannot shed blood or be injured.

Arthur Acquires Excalibur
Arthur acquires Excalibur with Merlin. Arthur asks the Lady of the Lake politely for the sword and she says she will give it to him in exchange for a request later on. He agrees, and he acquires Excalibur. Merlin tells him that the scabbard is far more valuable and never to lose it and always keep it with him.

Accolon
Morgan steals Excalibur and gives it to Accolon so that he can beat Arthur in battle and become the next King, however he fails and dies.

Morgan La Fay
Morgan steals the scabbard as revenge, because Arthur had killed her lover Accolon. She throws it into a lake. It is never seen again.

Arthur's Death
Bedivere throws Arthur's sword into the ocean after his 'death' so that Arthur can rise again one day.