Hi rx7,
Welcome to the forums. Your user name got my attention, as I have a 1984 RX7 GS that has 120K original miles on it. You don't see many references to RX's any more. I loved that car. I drove it the day it rolled off the showroom floor.
Are you sure that knife has a solid brass blade on it? It appears to have wear on the edges that are showing a stainless finish underneath. It might be the light, but what does a close inspection on the sharpened edge look like, brass? Generally that's where you'll see the underlying material, if it's only a surface coating that you're looking at.
It looks pretty cool. Does it have a manufacturer's mark on the blade, or inside the case?
I'll give you $3 for it right now, sight unseen!!
Alex