Any amount of combatives training leads the practicing handgunner to realize the value of a blade for contact distance fighting. There is no better place to carry this knife than in the appendix position so that it is accessible quickly, from most positions, and accessible to either hand. The priority, however, should be in using this blade with the support hand. This gun/knife combination drastically expands your defensive capability at contact distance.
While I have never dedicated much time to being a knife guy, and I certainly don’t train much in any of the traditional “knife fighting” techniques, I have carried a knife all of my adult life and have had basic training in employing a knife as a defensive tool. A knife is an essential emergency rescue tool to carry on your body anyway, should you need to free yourself or someone else from a seat belt or snag of some kind. Therefore, I suggest that most people who are invested in their own self-protection should know some basics of using an edged weapon for self-defense.
Historically, I always carried a folding knife. The primary purpose of the knife for me is as a utility or emergency cutting tool. However, even when carrying a folder I always keep it in my support-side pocket so that I can draw it with the support hand and I practice opening it efficiently and quickly. The problem with a folder, however, is the task of getting it open limits it as a self-defense tool as deploying the blade is hard to do when getting pounded on, even if you practice this task a lot.
For the past couple of years I have opted to carry a small fixed-blade knife in the AIWB position, opposite of my gun, and this is my preference whenever legal to do so (some jurisdictions are more strict on fixed blade carry than folder carry). While the small fixed blade still provides the emergency cutting capability, obviously, it proves a much more feasible backup defensive tool than does a folding knife.
I carry the knife on my support hand side appendix position (I am left-handed, so the knife rides on my right side, forward of the hips, opposite my gun) because if needed in self-defense it would likely be in an effort to retain the gun, or when the gun can’t come out. In my opinion, carrying a small fixed blade, AIWB opposite your gun, gives you maximum flexibility in employing the tool to defend yourself, should you need to.
If in a situation where the gun can’t come out to deal with a contact distance threat, perhaps due to the possibility of a gun grab or because there are innocents behind the adversary, going directly to the blade may be the safest means of defending everyone’s life.
Strictly Lethal Force
Bear in mind that the knife is strictly a lethal force weapon; it is in no way legally or ethically lesser force than the firearm. Therefore, the only justification for deploying the knife in self-protection is in order to ward off an imminent and deadly attack. If you are not justified to shoot, you are in no way justified to go to the knife.
Consider the Knife a Space Maker
As any well-educated handgunner should realize, pistols suck at stopping a determined threat short of a nervous system hit to the spine or brain. A small blade is even more challenged in ending hostilities. The only way to stop a determined attacker with a blade is to cause so much blood loss that the aggressor eventually shut down. This can take a long time. Cutting certain points of the body to mechanically disable the attacker is another option, but much harder to do in practice than in theory.
If forced to use a knife to defend yourself, perhaps because you have no firearm on you or the firearm can’t come out due to being in an entangled fight, consider the knife a space maker. We are not out to kill the attacker, we are out to force them to stop doing what they are doing. In this capacity, stabbing at the face and neck are more physically and physiologically devastating than stabbing at the body and this is more likely to cause the assailant to break off the attack, or at least to temporarily back off, so that you can escape if possible, or go to your firearm if needed.
Carefully Consider Justification for Use
While the very notion of needing to use an edged weapon on an attacker is more abhorrent to most people than the notion of using a gun, remember that the only justification for doing such a thing is to defend yourself against a violent and deadly attack. If facing an attacker that is armed, or if facing multiple attackers that mean you true harm, or if dealing with disparity of force, such as a small female defending herself from a large and violent male, then the edged weapon may be justified. If you pull out a knife and use it against a simple assault, such as a drunk pushing you, be prepared to be prosecuted for aggravated assault or murder. Knife or gun, the only justification is when facing a deadly threat that can only be dealt with by a lethal force response.
Here I am coming straight out to target areas in the face and neck. The curved profile of the TDI Knife (I am using the trainer version here) facilitates a natural punch out directly to target areas. With a traditional knife a reverse grip used with a hammer fist strike may prove superior for this technique compared to a saber grip.