You're right, it does sound rather French, likely from a Latin (Aegidinus?) or Germanic (Giselland?) root name. Now an '-and' suffixed name becoming '-aud' in French is a bit of a stretch, but not unexplainable. The next best place to look are the low-German languages. Dutch and Flemish frequently morph a name unrecognizable and then might add a Latin '-us' suffix later.