What's your Grip of Choice? What are your options, and in what situations? What are the limitations and advantages...What is your best course of action from your initial position?
You happened to hold a knife, a bayonet or stick and you have plenty of distance between your target before you engage. Obviously you could switch hold and approach before you get too close.
However, if you happened to have the time to just grip a weapon from the table, draw from a sheath, swing from your shoulder or from your belt, with your body in certain position to respond to a threat you simply have to know your limitations from that position and respond the best you can.
Drilling in most efficient techniques of each type of stance and grip will help program your mind and body in navigating the dangerous space of the hotzone safely. Then devising an overall tactical plan will make your life much easier and quadruple your safety.
When "sparring" with a knife and both training partners assume the position of front hand distracting and rear hand stabbing consider the following: The hand naturally is easier to use and maneuver free of the knife. In this scenario you will be forced to address your opponent's free hand with your own free hand. You need to deflect any attempt to grip, shove or even patting to avoid being taken out of balance or simply being distracted leading to loss of control of the opponents knife.
The knife attack or counter attack is becoming secondary. You are going to be in a closer range to begin with. Consider using a kick to the groin, knee or scissors kick to the chin if the time allows you. However if you have time for a kick, you might have time to switch position and grip.
Often knife training section of unarmed combat is limited to basic scenarios and then free sparring which has not much of a use for the general student populations, as their perception is limited in drawing sound conclusions. They later might feel a need to train more and with wrong assumptions start developing bad habits.
The knife however gives extension and reach far beyond the hand which makes if preferable for an attacker to hold the knife with his front hand. It could be used to reach the defender's free hand with a slash or preferably a poke directed at the free hand and then continuing with a second poke to the opponent's neck, body or the other hand if it was on its way.
The initial impact would buy a few split seconds or more of delay from the opponent. If the opponent with the free hand in front would try use it to lure the attacker, escape with it and use his back hand to counter attack, he would simply have no time to do this, while the attacker is aiming for the palm or back of the front hand positioned way in front of the body, since the body would be way back to bring and use the other hand in defensive and offensive maneuver properly.
You can assume methods you have witnessed from hidden camera crime scenes from crime trends analysis etc. But while all people learn, should you rely on the average for your training? If so perhaps you should rely on the average physical capacity and not on the average physical mentality.
Dogs are much faster in their bite and reach. By learning the limits of reach of the physics of the human body, and analysis of prioritization you learn to maximize your safety by minimizing your distraction.
How do you fit all this mass information into a short curriculum to help students gain sufficient hand-to-hand-combat or self defense skills? You need to consider a series of limited drills and comprehensive tactical approaches that work and can be learned in few hours helping students to gain the necessary understanding, trust and ability to apply these skills.
Twenty One Hours to learn the techniques and training drills and Eleven Hours for rehearsal. Of course the rehearsal stage could be extended according to the time allotted.