I think the vestigial pas d'ane would indicate a time frame (18th C.) much later than Cortes (16th C.). The markings you describe sound like a familiar makers mark... Try searching under "maker's marks" in the European arms & armor forum - there's a thread that documents many of the marks of the period.
Speaking of which, you might want to request one of the mods move your thread to the European weapons forum...
ETA: In looking through another book, it would seem other style elements, e.g., the symmetrical clamshell guard, might date this as earlier - maybe mid-late 17th Century?
