Unusual yes. Not original??? I would want to say for sure. I cannot see why the original makers and I say makers as I do not think the smith would have been capable of making the whole thing. The scabbard, handle and probably the engraving are likely to have been done by other specialists. I would agree that it does not look 19th century but worn as dress, I see no reason why the makers did not think they were making a really cool and fancy piece.
