The Spanish were once under the dominion of the Moors (think el Cid, KingFerdinand, and QueenIsabella), and (as somebody who has read quite a bit of history from as many perspectives as possible in as many different "situations" as possible) there could have been some "borrowing" from both sides of the coin concerning Xavier. It might have come from a Moorish name, but, then again, not necessarily.
By the way, Basque is one of the few languages still in existance that has "remained" almost "pure" since ancient Roman times (according to a couple of sources I have. :rolleyes:.) I'm still looking into that claim.