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.
Norns
In the Calibur arc of Sword Art Online, Urðr appears to Kirito's party and gives them a quest to retrieve the sword Excalibur from Thrymheim before the last beast-type Evil God is killed, restoring Jötunheimr to its former glory. Upon successful completion of this quest, Urðr reappears to Kirito's party, along with her sisters Verdandi and Skuld. They thank them for completing the quest, and allow them to keep Excalibur. Other figures and elements from Norse mythology also appear in this arc, including Thrym, Freyja, Thor, and Mjölnir.