Excalibur is the sword of King Arthur from Arthurian legends. It is said that it has magical powers and is a mark of Arthur’s rightful sovereignty of Great Britain. Some legends equate it with a Sword in the Stone while other hold them separate.
Excalibur is mentioned for the first time in Welsh legends in 10th century, poem Preiddeu Annwfn and the prose tale Culhwch and Olwen as a Caledfwlch (caled ("battle, hard"), and bwlch ("breach, gap, notch")). In Culhwch and Olwen, Arthur holds it as his most valuable possession and Arthur's warrior Llenlleawg the Irishman uses it to kill the Irish king Diwrnach. The sword is also mentioned in “The Mabinogion”, collection of eleven prose stories collated from medieval Welsh manuscripts.
In 15th or 16th century in the play “Beunans Ke”, Arthur's sword mentioned as Calesvol which is a Middle Cornish variant of the Welsh Caledfwlch.
Geoffrey of Monmouth, a cleric and one of the major early British historians, mentions Excalibur in his “History of the Kings of Britain”. Because “History of the Kings of Britain” was written in Latin, Caledfwlch is written as Caliburnus. Name of the sword changed further as “History of the Kings of Britain” spread throughout the continental Europe and the name changed in Calabrun, Calabrum, Calibourne, Callibourc, Calliborc, Calibourch, Escaliborc, and Escalibor among others to take popular form Excalibur. Other prose works started mentioning Excalibur after that.
In them there are many stories how Arthur came into possession of Excalibur. In Robert de Boron's Merlin, sword was placed in the stone and only “a true king” could pull it out. Arthur pulled it out and proved himself as a divinely appointed king or true heir of Uther Pendragon. Vulgate Merlin Continuation, part of the Lancelot-Grail cycle explicitly says that this sword was Excalibur. In Post-Vulgate Merlin, Excalibur was given to Arthur by the Lady of the Lake after he became a king. At his dying bed, In the Vulgate Mort Artu, Arthur orders Griflet, one of his first Knights of the Round Table, to throw the sword into the enchanted lake but Griflet refuses twice. Third time he throws it and a hand of the Lady of the Lake emerges from the lake to catch it.
When the Excalibur was drawn for the first time by Arthur, in the first battle that tested Arthur's sovereignty, its blade blinded his enemies “with the light of thirty torches”. Excalibur's scabbard was also magical. Some legends say that wounds that loss of blood cannot kill the bearer of the scabbard while others say that wounds would not bleed at all. It was also said that it had inscriptions on both sides of the blade. On one “Take me” and on the other “Cast me away”.
Casting of the sword in the lake maybe has a historical origin. Ancient Britons had a tradition to throw a warrior’s treasured possessions into a lake as an offering to the gods which would in turn grant them safe passage to the afterlife.