Well if it’s made of brass it looks like brass knuckles and the stars represent what you might see after being hit with it. (No idea). Nice find. Congrats
I agree with dug... it is most probably a belt-tip. It's the right size for that, and has the right shape for "threading" it through a belt-loop or similar setup. Answering ColtsPop's query... it could be from as early as the 1800s, but if so, it is definitely not a civil war Military relic.
All of us diggers (including me) need to keep in mind that a relic which dates "from the civil war era" doesn't mean it was used by a soldier in the civil war.
I agree that a belt tip is what I first thought of when I read this post. However, my big question is, if it was how was it attached? It doesn't appear to have any attachment hooks or remnants of any on the backside from your photos.