Recently ended on ebay. I have never seen a Tiv dagger that wasn't one-piece steel, but obviously I haven't seen everything. Doesn't strike me as african, though.
I thought this might rather be a bichwa of some type; although I haven't seen a horn-handled bichwa either, I've seen Indian knuckle-dusters and other sorts of parrying weapons made out of carved horn. Of course, it is rather long (blade alone is 29 cm) and lacks the typical shape, so it probably isn't a bichwa either.
Some other sort of tool or weapon? Chinese, perhaps?
Perhaps someone has seen the like?