Wachmann, follow the coat of arms if you can. The crown above the shield almost always indicates some type of royal title from baron to duke Von so and so. It can be hard to trace but it is listed somehere in a table of coat of arms. If you do not have the name of the family then you must go to an Armorer. I don't know if I spelled that corectly but it is a book or list of coats of arms that then gives you the family name. There are those who can decifer much of what is on the shield by standard convention. The value of the dagger rests with the titled owner or royal family involved. David