Ethil wrote...
No? Caliburn is The Sword in the Stone, Excalibur is another sword that Arthur gets after he (or she) is crowned. I think they even say it in F/SN.
I know this isn't the point of the topic, but my History degree almost burst into flames. In the real-life legend, The Sword in the Stone was only known by that name, and eventually broke. Excalibur, and the un-named magical sheath, were given to Arthur by the Lady of the Lake. The rest, as they say, is history.
Fate/Stay Night can say whatever it wants to about its version, though. And on topic, I'd still want that sword, only if it were a little longer.