Couldn't help but read you above post after the one on diminishing teaching standards.
Imho black belt only means someone was able to pass the requirements of a particular testing curriculum. It should be no indicator of a person's real life combat ability imho (though in some cases it may be applicable). As one may see in many of the proven civilian self defence programs, situational training and conditioning of reflex and flinch reactions do more to set up successful responses than learning a bunch of techniques in a static or cooperative manner (enter the Aikido and it's effectiveness question
I'm sorry to hear about the individual who got injured, but there are
ways to defend against these things if escape is not an option. The key in training is to deal with the particular scenario or train one's instinctive reactions to operate in a manner conducive to defending oneself from a variety of knife attack scenarios, focussing on principles of application and reaching the opponent safely. The ending techniques are very secondary imo.
I've had a 4th kyu student who got attacked by a mugger with a knife. Due to the ridiculous amounts of resistance tanto randori we do with someone trying to stab you, he was able to "just react" and got the mugger into sankyo. The guy took off leaving him with the knife in his hand and very shocked I might add as reality slowly set back in.
It's not what we train so much, but how we train that makes us effective imho.
Just my 2 cents.