It certainly looks like and 1800's razor from Sheffield or the US. The scales are horn and can be rehydrated with some neatsfoot oil. The crack is a pretty serious issue though. If the grind is not too thin you could remove the crack along with much of the stabilizer. By the looks of the razor though, that would be a very bad idea. The other option would be to remove width from the blade. Also a bad idea in this case. That thing has tons of character though, and a very nice patina. If that were my great uncles razor, I'd soak the scales, remove any rust and mount it in a shadow box for display.