Excalibur
Geoffrey of Monmouth, in his "Historia Regum Britanniae" ("The History of the Kings of Britain", c. 1136), Latinised the name of Arthur's sword as "Caliburnus" (potentially influenced by the Medieval Latin spelling "calibs" of Classical Latin "chalybs", from Greek "chályps" ["χάλυψ"] "steel"). Most Celticists consider Geoffrey's "Caliburnus" to be derivative of a lost Old Welsh text in which "bwlch" (Old Welsh "bulc[h]") had not yet been lenited to "fwlch" (Middle Welsh "vwlch" or "uwlch"). In the late 15th/early 16th-century Middle Cornish play "Beunans Ke", Arthur's sword is called "Calesvol", which is etymologically an exact Middle Cornish cognate of the Welsh "Caledfwlch". It is unclear if the name was borrowed from the Welsh (if so, it must have been an early loan, for phonological reasons), or represents an early, pan-Brittonic traditional name for Arthur's sword.
Prince Valiant (1997 film)
The story is based on the myth of King Arthur. A young, inexperienced squire Valiant, masquerading as Sir Gawain, is sent to accompany the Welsh princess Lady Ilene, a guest at Camelot, on her way back home. Little does he know that meanwhile, Arthur's wicked sister Morgan has retrieved a spellbook from Merlin's tomb and convinced the Viking warlord Sligon, ruler of the kingdom of Thule, to steal the magical sword Excalibur during a joust tournament.