That's one I haven't seen before. Do you have a membership on Blade Forums? If you postthose pic's asking about it under the Buck section you will receive some info for sure. Where did you get it?
actually all my older ones are the ones thats squared off on the edges.
I have seen customized work some folks do by grinding and sanding the rough edges off of there lock backs to produce an effect like this. Not sure but it could be. Have you asked your uncle who gave it to you?