wow, i'd get onto hunting knives collectors forums and show them your pics and get them to at least name the type of knife it is, then start googling for more info on it and then contact independent valuation houses.
there's an antique show on BBQ, cant think of the guys name, he'd have a website, maybe you could contact him.
Telling people that it was valued at more than the value of your house a few years back will certainly get you some attention and help!
