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.