E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Sword Excalibar (The).
At the death of Uter Pendragon there were many claimants to the crown; they were all ordered to assemble in the great church of London, on Christmas Eve, and found a sword stuck in a stone and anvil with this inscription: He who can draw forth this sword, the same is to be king. The knights tried to pull it out, but were unable. One day, when a tournament was held, young Arthur wanted a sword and took this one, not knowing it was a charmed instrument, whereupon he was universally acknowledged to be the God-elected king. This was the sword of Excalibar. (History of Prince Arthur, i. 3.)
The enchanted sword (in Amadis of Gaul). Whoever drew this sword from a rock was to gain access to a subterranean treasure. (Cap.CXXX.See also caps. lxxii. and xcix.)