What is Excalibur?

Answer 1

The medieval Story of Merlin attributed to Robert de Boron first tells of the sword that was magically put in a stone and anvil in a prophecy that whoever pulls the sword out of the stone will be king. Arthur, then still a youth, pulled it out and was made king. It is not explicit here whether this sword is to be identified with Arthur's famous sword Escalibor/Caliburn, which is first named Excalibur by Sir Thomas Malory in his Le Morte d'Arthur.

In an expanded version of the Story of Merlin, generally known as the Vulgate Merlin, an addition covers the first five years of Arthur's reign and the sword is explicitly identified as Excalibur.

In another expanded version of the Story of Merlin, generally known as the Post-Vulgate Merlin, the sword in the stone and Excalibur are two different swords. Arthur breaks his sword, perhaps to be identified with the sword from the stone, in a battle with King Pellinor and Merlin persuades a damsel to give Arthur a new sword which is held by a arm and hand which rises from a lake. (In Malory's retelling this damsel is called the Lady of the Lake.) The sword is later named Escalibor.

In Welsh tales the sword is named Kaletvwlch, usually normalized in translation to Caledflwch. This looks like a Welsh version of the Irish sword name Caledbolg. Caledbolg was the sword of the Irish heroes Fergus mac Leide and Fergus mac Roch.

Escalibor/Caliburn/Kaletvwlch might possibly be a relic of Roman times (the Romans possessed Britain for a couple of centuries). But the name Escalibor or Kaletvwch cannot be a derivative of the Latin phrase incidere chalybs ('cut steel') which supposedly refers to the roman swords being repetitively tempered and therefore harder and capable of notching or even breaking the crude iron swords of the Anglo-Saxon invaders. Linguistically, this supposed derivation does not work. And the phrase is rare or non-existent in Latin texts. Escalibor/Caliburn/Kaletvwlch is never called "the singing sword" in any medieval text.

Answer 2

Excalibur is a legendary sword from Arthurian legend, often associated with King Arthur. It is said to have magical properties and can only be wielded by the rightful king of Britain. The sword is sometimes depicted as being given to Arthur by the Lady of the Lake.

Answer 3

Humans?

,.. of course?