Before I start, let me make one thing clear. Krav Maga does not teach butchering techniques. These can be applied to dead animals and wounded humans.
Pure Krav Maga Knife Defense Drills incorporate selected few distilled Original Krav Maga techniques presented in the below linked video clips.
In fact in Pure Krav Maga we do not deal with all realistic scenarios, but just the best theoretical and practical scenarios.
We use these scenarios to learn the principles of how to respond to any knife attack with a simple formula. Then we drill the proper response with Pure Krav Maga Techniques.
Rather than exploring endless possibilities, the most efficient approach is chosen where an opponent might hold a knife in a any possible grip with the front or cross hand or hiding it behind his back. This includes various methods of approach to close and enter the hotzone.
Pure Krav Maga takes the assumption that the first cut is the most critical as it creates distraction facilitating further injury and lack of quick response for further fighting.
Pure Krav Maga techniques provide its users the optimal training method of defense. The training method first considers, the type of bio-mechanical motion expected from the way the opponent is standing: Straight-stab, slash, bottom-up, and top-down and then the differentiation of response whether the attacker is holding the knife in his front hand or cross hand. In addition technical solutions in form of techniques are variant depending which sides of the bodies of both opponents face each other as they get closer to the hotzone.
Pure Krav Maga does not explore what you are doing far out of the hotzone. It is only exploring what is in a split second reach without losing the element of surprise.
The reason is due to the reaction time principle in which human brains need a split second to plan an action of attack or defense and another few split seconds to execute the maneuver.
Very simple, if you hold a knife on a certain plane, your body can create leverages with its limbs to drive the knife into a poke, cut or slash, or tear in various angles. And if you combine that fact with a straight line from this position is the fastest way to reach the target, you become more efficient.
Watch Efficient Use of a Knife
Watch Bare Hands vs. Knife
Watch Kicks vs. Knife