A langet is a piece of iron on a hafted weapon like an axe that extends down the haft. The purpose to to stabilize the head and protect the haft from damage - In these boarding axes, for example, type II and III have langets, whereas type I does not:
http://www.boardingaxe.com/america.htmlThe shell on the guard was a pretty common element, not only for hunting swords but also for some infantry hangers. I don't know where exactly it comes from, but at a guess I'd say it is a development from certain types of sword guards that had a disc attached to the side of the guard to protect the knuckles (which were themselves a development from earlier Renaissance-era swords with rings there). Probably mostly a decorative element, but it may have also served to help keep water and debris out of the mouth of the scabbard while the sword was sheathed. Some late Medieval swords had leather flaps on the hilt for that purpose, I believe.
I believe that this one is most likely 19th century, though I think it possible that it might have been made early in the 20th, as these old traditional forms were produced up until the 1940s, I think. Most likely German or Austrian, I think.