It is also not possible to gauge the requirements of building a successful martial art combat knife defense program without having first been exposed to expert knife practitioners.
Training with edged weapon specialists quickly dispels any commonly held misinformed beliefs or martial art knife defense myths.
The reality is that there are considerable differences in the skill sets being taught at many martial art combat classes and those that are needed to effectively deal with the reality of a knife or edged weapon attack.
A primary issue with many traditional combat martial art styles and even Western Boxing is that they can teach and entrench distancing that gives a competent knife exponent the chance to cut the opponents extremities at will.
Another issue that is rarely addressed in traditional martial art combat is that in order to counterstrike an armed opponent you must first get past a bladed hand that can with a minimum of effort, deliver a devastating and even fatal strike to the unarmed combatant.
The fact is that a blade strike requires little or no pullback preceding the strike, can cut going out as well as coming back and can deliver devastating injury with very small movements even when used in the front hand.
Knife defense training itself can initially offer more failure than success in its early stages with many of the traditional martial art combat concepts of distancing needing to be reviewed and adjusted to more realistic distances.
It is the defenders responsibility to adjust their distance to their attacker and allow for the natural reach of the opponent as well as the extra reach added by the length of the particular blade they are using.
Anticipating and recognizing the kind of strike that is coming at you must be tempered with the ability to "hold ones nerve" and not attempt to block or parry something that has not yet been fully thrown, as this can lead to misjudging the strike and missing the counter or block completely.
The result of that is usually being struck at full speed with the blade on the head or body.
Keeping the correct distances will go towards keeping you as the defender in the "safe" zone as opposed to any other range which is of course "unsafe".
Physically reaching out and looking for the counter or parry to the anticipated blade strike and not waiting for it to come to you is a fundamental error and generally results in injury to the defender.
Not allowing the attacker to fully extend and commit to their strike is a mistake in that the attacker can change the trajectory of the blade strike and "cut short" if they see that you are going to counter before he has committed.
Commonly referred to as "putting your hand in the fan", this mistake can result in serious blade injury to the hands and arms.
The bottom line is that traditional martial art combat practitioners should seek out and work with an edged weapon specialist in order to fully appreciate the different ranges in distancing that is required in edged weapon defensive tactics or even weapon to weapon sparring practice.