I've had one on my keychain for probably twenty years. I keep it closed with a rubber band wrapped around the blade and "handle." I've also seen rubber tubing mentioned as another good way to stop a P-38 from stabbing you in the leg.
I've always carried it for "just in case" use, so, I haven't had the chance to learn that it'll get dull, yet.
Good information from the long time users, as usual!
GeoThorn