Hello Rob,
Another vote for deteriorated horn - looks quite similar as the kukri to me.
I'd also suggest that such pieces offer opportunities like extensive repolishing projects; never throw any bits and pieces away, of course. And I also agree that any genuine and old piece is collectable as it is a still extant material link to a usually past culture even if the monetary value may be approaching zero.
And, mind you, there never can be too many barungs - keep them coming!
Regards,
Kai