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.
Ratscalibur
After moving to the big city, 11-year-old Joey is turned into a rat by a rat magician (or "Ragician") and sent on a mission to report to Uther, king of the rat kingdom Ravalon. On the way, he inadvertently pulls the legendary Spork, named Ratscalibur, from the legendary Scone, and is hailed as the prophesied hero. Subsequently, he is expected to go on a quest to save the rats from the wicked wizard Salaman, if he is to be restored to his human form.There are many allusions throughout the book to the Arthurian legends. The book's title is a pun on Excalibur, the sword wielded by King Arthur, and much of its premise is a pastiche of tales of medieval chivalry and knights errant. Other allusions include the character Parsifur, a pun on the knight Percival; King Uther being an allusion to Uther Pendragon, the father of King Arthur; Ravalon being a pun on the legendary island Avalon; and the legendary "Spork in the Scone" a reference to the Sword in the Stone. Squirrelin is also a reference to Merlin.