My automatic knife is a Glock 43. It barks over here and bites over there. I am to damn old to get in a knife fight. :)
I don't intend to get into a knife fight but if someone gets in your face where you cannot get to your Glock and you can get to your knife then you can back them off far enough to use your Glock effectively. The knife I carry is for practical purposes and to back off a perp that is too close for me to pull my CCW.