What was the name of King Arthur's sword?

Answer 1

The sword was named Kaletvwlch in medieval Welsh texts (usually modernized as Caledfwlch in modern versions of those texts). In medieval French tales the sword is named Caliburn, later fancied up to Escalibor. Sir Thomas Malory in his Le Morte d'Arthur rendered the name as Excalibur.

Because Malory's work was so popular in English, that form of the name is the one which later English authors mostly use. It is also used in some English translations of medieval works where the name is found differently in the source language.

Some medieval romances give other minor variations in spelling.

According to Geoffrey of Monmouth's Historia Regum Britianniae (the earliest surviving biography of Arthur) the sword Caliburn had been forged in the Island of Avalon but this account tells nothing of how Arthur obtained it. According to the medieval, so-called Vulgate Merlin account, Caliburn was identical to the nameless sword which Arthur pulled from the sword and so became king. According to the medieval, so-called Post-Vulgate Merlin Arthur was given Caliburn after he became king by a lake fay and it is unrelated to the sword in the stone.

A version of the Post-Vulgate Merlin occurs in a manuscript named Cambridge Add. 7071 in which material from the Vulgate Merlin is also included and which according identifies Escalibor with the sword in the stone, but later in contradiction identifies it with the sword given to Arthur by the lake fay. Sir Thomas Malory derived the earliest section of his Le Morte d'Arthur from a similar combined account and so gives both contradictory origins for Excalibur with no attempt at an explanation.
Excalibur