"...okay, now put your right hand in your front pocket and pretend your hand is broken, pinned down, missing, whatever... and you need that knife... can you reach it?"

Reminds me of an incident that happened to me a few years back. Getting out of the car. Locked door from inside, dropped keys in right front pocket. Immediately slammed door on right thumb, pinning it. Ouch! Left hand could easily reach knife in left pocket. But I didn't want the knife - I wanted the stupid keys!!!

p.s. - It's amazing just how flat a thumb can get, and still survive without permanent damage!