And what is this one??

[Dmitry]

This is a European hunting dagger in my opinion, possibly even Russian in origin, as was suggested above. And if I were to be really speculative, I would go with the end of 18th century to the mid-1800s. I am not sure that the rivet heads are original. They look too plain, and don't "work" with the rest of the hilt. Same goes for the brass eyelet.
My $.02