1590s, "one of the 12 knights in attendance on Charlemagne," from Middle French paladin "a warrior" (16c.), from Italian paladino, from Latin palatinus "palace official;" noun use of palatinus "of the palace" (see palace).
The Old French form of the word was palaisin (which gave Middle English palasin, c. 1400); the Italian form prevailed because, though the matter was French, most of the poets who wrote the romances were Italians.[paladin etymology, paladin origin, 英语词源]