[1] The sword given to the young Arthur by the Lady of the Lake in the tradition that began soon afterwards with the Post-Vulgate Cycle is not the same weapon, but in Le Morte d'Arthur both of them share the name of Excalibur.

The name Excalibur ultimately derives from the Welsh Caledfwlch (Breton Kaledvoulc'h, Middle Cornish Calesvol), which is a compound of caled, 'hard', and bwlch, 'breach, cleft'.

(As Thomas Malory related in his English-language Arthurian compilation, the 15th-century Le Morte d'Arthur, "whoso pulleth out this sword of this stone and anvil, is rightwise king born of all England.

[22] After many of the gathered nobles try and fail to complete Merlin's challenge, the teenage Arthur, who up to this point had believed himself to be biological son of Ector and went there as a squire to his foster brother Kay, succeeds effortlessly.

[24] Eventually, in the cycle's finale Vulgate Mort Artu, when Arthur is at the brink of death, he enigmatically orders his surviving knight Griflet to cast Excalibur into a nearby lake.

After two failed attempts to deceive Arthur, since Griflet felt that such a great sword should not be thrown away, he finally does comply with the wounded king's request.

In the Post-Vulgate Mort Artu, it is this sword that is eventually hurled into the pool at Camlann (or actually Salisbury Plain where both cycles locate the battle, as do the English romances) by Griflet in the same circumstances as told in the story's Vulgate version.

In addition, it said that when Excalibur was first drawn in combat, in the first battle testing Arthur's sovereignty, its blade shone so bright it blinded his enemies.

[29] In Chrétien de Troyes' late 12th-century Old French Perceval, Arthur's nephew and best knight Gawain carries Excalibur, "for at his belt hung Escalibor, the finest sword that there was, which sliced through iron as through wood"[30] ("Qu'il avoit cainte Escalibor, la meillor espee qui fust, qu'ele trenche fer come fust"[31]).

This statement was probably picked up by the author of the Estoire Merlin, or Vulgate Merlin, where the author asserts that Escalibor "is a Hebrew name which means in French 'cuts iron, steel, and wood'"[32] ("c'est non Ebrieu qui dist en franchois trenche fer & achier et fust"; the word for 'steel' here, achier, also means 'blade' or 'sword') and comes from medieval Latin aciarium, a derivative of acies 'sharp', so there is no direct connection with Latin chalybs).

[38] Another late Iberian romance, Tirant lo Blanch, features Arthur who was brought back to life by Morgan and then wandered the world for a long time while mad and able to talk only when having Excalibur in his hands.

Finally, Morgan finds her brother imprisoned in the contemporary (15th-century) Constantinople, where she restores him to his mind by making him gaze upon his reflection in Excalibur's blade.

The challenge of drawing a sword from a stone (placed on the river just outside Camelot) also appears in the later Arthurian story of Galahad, whose achievement of the task indicates that he is destined to find the Holy Grail, as also foretold in Merlin's prophecies.

This powerful yet cursed weapon, known as the Adventurous Sword among other names, has also come from Avalon; it is first stolen and wielded by Balin until his death while killing his own brother, then is briefly taken up by Galahad, and eventually is used by Lancelot to give his former friend Gawain a mortal wound in their long final duel.

Irish mythology features Caladbolg, the sword of Fergus mac Róich, which was also known for its incredible power and was carried by some of Ireland's greatest heroes.

Marmiadoise's powers (such as causing wounds that would never heal) are in fact so superior compared to those of Excalibur that Arthur gives his old sword to Gawain.

[2][5] Historically, a sword identified as Excalibur (Caliburn) was supposedly discovered during the exhumation of Arthur's purported grave at Glastonbury Abbey in 1191.