first thing he should've noticed is the hand behind this guys back. always look at the hands because hands hurt people, carry weapons, etc. he should've aimed to either grab the hand behind the guys back or run away.
please do not let it be said that stabbing cannot and should not be used IMO it must be balanced - against\alongside\with - all of the simple extended slashing blocking striking techniques which generally offer more effectiveness and the utility of more protection from deploying moves and counter moves.
well, a puncture (I don't want to use the word stab. Thats only one type of attack that could result in a puncture. The fencing lunge would be an example of a puncture attack that is not a stab) needs to be set up. It would be foolish to make that the first strike. But grabbing someone's arm with one hand and thrusting the knife with the other would be a good example. Another would be to get them to drop their hands by cutting at their arms or hands, and once those hands go down, then bam.
If you watch this video (versus the KM frontline video which is very good) you will see that for no reason (a little suspiciously for the sake of the script perhaps) he expects the knife, acknowledges it, he kicks which is a goog ranging stike, but then against all known instinct reaction (think defensive wounds people focus on knives when being attacked) deliberately ignores the knife deploys no other strike\block\hold
The the effectiveness of these methods is enhanced because of several additional factors\influences long weaponry - with preferred use of medium/long length shield and formation tactics (and as was proven in the race and miners riots in UK 1980s and the race and anti war riots in US in 1980s not wishing photographic images of overshoulder clubbing by police of rioter/protestors)
Undoubtedly the stabbing moves have their place, and there are classic examples of this where this was the only trained principle method in combat lethal - the roman gladdius sword, the italian stilletto knife and the sykes fairburn commando dagger in surprise neutralization/murder -non lethal unbladed versions of above - police riot control long baton\bo and arrest and restaint truncheon\short baton
Just because puncture wounds are more dangerous doesn't mean that stabbing is always preferable to slashes. They are two separate issues, and there is a time for both. I would agree that there is some criticality for puncture wounds, but if you manage to punture someone especially in the torso, its going to be more serious damage. As for non edged weapons (eg. bo) involve the "move across" principle. There are strikes that are stab like (one looks alot like hitting a billiard ball).
I'm a girl.