The cross-guard is steel, with acorn-shaped quillons. The grip has acquired a fine uniform patina and age craquelure. The pommel cap is sterling silver, hall-marked with a maker's cartouche J*B. A nice touch is the presence of a thin sterling silver washer between the grip and the cross-guard, a feature I haven't seen before.
I believe this piece is a hunting dagger, and dates from the late 1700s to the early 1800s.
An unusual and a very expressive piece!