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.
Excalibur rifle
Excalibur is an assault rifle that is derived from the INSAS rifle, which is the standard rifle of the Indian Army. The rifle has many improvements over the INSAS rifle and was slated to replace the INSAS as the Indian Army's standard assault rifle; however, the Indian Army put the replacement out to tender in September 2016. The Excalibur will be manufactured by the Ordnance Factories Board in Ordnance Factory Tiruchirappalli, Small Arms Factory, Kanpur and Ichapore Arsenal.