From the pictures, I'm fooled. It really looks like stained wood to me...I can see a fibrous structure, but it could be wood grain. If you didn't bring the possibility that this might be a horn-hilted dagger, I'd be sold that you're showing a wooden object

I have a piece with antler hilt, but left in its rough state...I had no idea what polished antler looked like.
Can you post more pics of the whole thing?
Emanuel