My buddy has a USMC issue Kabar strapped to his rollcage. I asked him about it one day and he told me about getting trapped by the seatbelt in a rollover one time and the rig caught on fire. He barely managed to get out and said it'll never happen that way again.

I keep a razor-sharp S&W pocket knife clipped to my front left pocket 24/7. I need to try it out on an old seatbelt one day, but I'm sure it'll do nicely.