The goal is to escape, not annihilate the enemy. That's ego talking, the need to punish anyone who dares touch you.
You know your friends better than we might presume to, but in the use of force continuum some people will not be made to break off or be incapacitated by anything more than great injury. Small tools required proportionally greater skill to help ensure your safety. conw and you and I would be more successful with your small knife or a Bic pen or kubaton because we've trained in how to apply their limited injury potential to the optimum use. If the folks that have commented on Sam's knife have equivalent training then they're either bloodthursty or they're envisioning a worst case PCP/Meth/Prison Sifu opponent that has to be destroyed to gain escape.