Like most of us, I have arrived on the scene of an accident before first responders.
I know basic first aid and CPR. I've used both a few times. I had to break out a window and cut a seatbelt at one accident scene (Army medic and nurse on scene wanted the guy out like NOW- he ended up DOA).
My Ka-Bar Warthog knife is cool, but this is cooler and potentially more useful:
The CRKT MAK-1 system. M.A.C. 10" O.L. kinfe with a 3" blade, dull chisel end, carbide window breaker tip on the other end- along with other stuff. This is held in the Cordura sheath with the Extrik-8-R seat belt cutter (brass knuckles? heh heh).
Tremendously useful, non-tactical durable kinfe combo set designed by a firefighter.
-p.