Excalibur is the legendary sword of King Arthur, sometimes attributed with magical powers or associated with the rightful sovereignty of Great Britain. Sometimes Excalibur and the Sword in the Stone (the proof of Arthur's lineage) are said to be the same weapon, but in most versions they are considered separate. The sword was associated with the Arthurian legend very early. In Welsh, the sword is called Caledfwlch.
In Welsh legend, Arthur's sword is known as Caledfwlch. In Culhwch and Olwen, it is one of Arthur's most valuable possessions and is used by Arthur's warrior Llenlleawg the Irishman to kill the Irish king Diwrnach while stealing his magical cauldron. (Irish mythology mentions a weapon Caladbolg, the sword of Fergus mac Roich. Caladbolg was also known for its incredible power and was carried by some of Ireland's greatest heroes.)
Though not named as Caledfwlch, Arthur's sword is described vividly in The Dream of Rhonabwy one of the tales associated with the Mabinogion:
Then they heard Cadwr Earl of Cornwall being summoned, and saw him rise with Arthur's sword in his hand, with a design of two chimeras on the golden hilt; when the sword was unsheathed what was seen from the mouths of the two chimeras was like two flames of fire, so dreadful that it was not easy for anyone to look. At that the host settled and the commotion subsided, and the earl returned to his tent.
From The Mabinogion, translated by Jeffrey Gantz
Excalibur in Cornwall
In the late 15th/early 16th century Middle Cornish play Beunans Ke, Arthur's sword is called Calesvol, which is etymologically an exact Middle Cornish cognate of the Welsh Caledfwlch. It is unclear if the name was borrowed from the Welsh (if so, it must have been an early loan, for phonological reasons), or represents an early, pan-Brittonic traditional name for Arthur's sword.
Caliburn to Excalibur
Geoffrey of Monmouth's History of the Kings of Britain is the first non-Welsh source to speak of the sword. Geoffrey says the sword was forged in Avalon and Latinises the name "Caledfwlch" as Caliburnus. When his influential pseudo-history made it to Continental Europe, writers altered the name further until it finally took on the popular form Excalibur (various spellings in the medieval Arthurian Romance and Chronicle tradition include: Calabrun, Calabrum, Calibourne, Callibourc, Calliborc, Calibourch, Escaliborc, and Escalibor). The legend was expanded upon in the Vulgate Cycle, also known as the Lancelot-Grail Cycle, and in the Post-Vulgate Cycle which emerged in its wake. Both included the work known as the Prose Merlin, but the Post-Vulgate authors left out the Merlin Continuation from the earlier cycle, choosing to add an original account of Arthur's early days including a new origin for Excalibur
The story of the Sword in the Stone has an analogue in some versions of the story of Sigurd (the Norse proto-Siegfried), whose father, Sigmund, draws the sword Gram out of the tree Barnstokkr where it is embedded by the Norse god Odin.
In several early French works such as Chrétien de Troyes' Perceval, the Story of the Grail and the Vulgate Lancelot Proper section, Excalibur is used by Gawain, Arthur's nephew and one of his best knights. This is in contrast to later versions, where Excalibur belongs solely to the king.
The Lady of the Lake offering Arthur Excalibur, by Alfred Kappes (1880)
In many versions, Excalibur's blade was engraved with words on opposite sides. On one side were the words "take me up", and on the other side "cast me away" (or similar words), alluding to Jonah 1:12. This prefigures its return into the water.
In addition, when Excalibur was first drawn, in the first battle testing Arthur's sovereignty, its blade blinded his enemies. Thomas Malory writes: "thenne he drewe his swerd Excalibur, but it was so breyght in his enemyes eyen that it gaf light lyke thirty torchys."
Excalibur's scabbard was said to have powers of its own. Injuries from losses of blood, for example, would not kill the bearer. In some tellings, wounds received by one wearing the scabbard did not bleed at all. The scabbard is stolen by Morgan le Fay and thrown into a lake, never to be found again.
Nineteenth century poet Alfred, Lord Tennyson, described the sword in full Romantic detail in his poem "Morte d'Arthur", later rewritten as "The Passing of Arthur", one of the Idylls of the King:
:There drew he forth the brand Excalibur,
And oer him, drawing it, the winter moon,
Brightening the skirts of a long cloud, ran forth
And sparkled keen with frost against the hilt:
For all the haft twinkled with diamond sparks,
Myriads of topaz-lights, and jacinth-work
Of subtlest jewellery.
Arthur's other weapons
Excalibur is by no means the only weapon associated with Arthur, nor the only sword. Welsh tradition also knew of a dagger named Carnwennan and a spear named Rhongomyniad that belonged to him. Carnwennan ("Little White-Hilt") first appears in Culhwch and Olwen, where it was used by Arthur to slice the Very Black Witch in half. Rhongomyniad ("spear" + "striker, slayer") is also first mentioned in Culhwch, although only in passing; it appears as simply Ron ("spear") in Geoffrey's Historia. In the Alliterative Morte Arthure, a Middle English poem, there is mention of Clarent, a sword of peace meant for knighting and ceremonies as opposed to battle, which is stolen and then used to kill Arthur by Mordred.