I have knife with a 7" blade, hollow handle and a little nifty compass in the cap. I would call this knife a "Rambo Knife". VA law makes no mention of blade length and only covers dirks, bowies, num chucks (don't even know how to spell num chucks) etc....
So I would assume "Rambo" knives are legal.........well maybe not
I bet most of the law makers in this country don't even know what a Dirk is. I think all the knife laws in this country were writen back in the 1800's.