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.
Lê Lợi
Many legends and stories were told about Lê Lợi. The most famous story concerns his magical sword. Much like King Arthur and his sword Excalibur, Lê Lợi was said to have a magic sword of wondrous power. One story tells that he obtained the sword, inscribed with the words 'The Will of Heaven' (Thuận Thiên) from the Dragon King (Vietnamese: Long Vương), a demi-god to the local people, who decided to lend his sword to Lê Lợi. But there was a catch: the sword did not come straight to him in one piece.