I will say up front, as I have written a number of times before, I am by no means a “knife fighter.” I am generally a “fight avoider” and a knife fight would be the sort of conflict I would truly wish to avoid at all costs. I am, however, a proponent of always carrying a knife, as in every waking moment, unless you have to enter a vicinity in which it is prohibited. The primary role of the knife for me is as a utility tool, and a potentially lifesaving tool at that. If you must cut somebody free of a seatbelt or some other emergency task, you need to have a knife on you.
I have always carried a folding knife for this exact reason, although I will say that I have for many years carried a fast-deploying folder and I wear it on my support side. The reason for this is that, should I need to press the knife into self-defense, it would most likely be under circumstances in which I cannot access my gun, or bringing the gun into play would be hazardous compared to getting the knife out. If you have done any amount of training for contact-distance fighting, you know that a gun can be taken from you fairly easily; the knife is much more retainable and can prove the better weapon for contact distance.
So, although the knife serves a secondary role in self-defense for myself, it is still a secondary weapon on the body. No matter how practiced you are at deploying a folding knife, and I have practiced it quite a bit, a fixed blade knife is, of course, faster and more reliable in deployment. For this reason, serious knife guys use fixed blades if not constrained by legal issues (which is a concern, many states restrict fixed blade carry but permit most folders, so be aware of this). Being a dedicated “not a knife guy” I never bothered carrying a fixed blade knife, outside of when hunting in the woods. However, I came to the conclusion recently that a very small fixed blade might serve a purpose for myself. Obviously, worn center line, the blade facilitates much faster deployment than any folder, and it can also be accessed by either hand. Second, and this is a big one for me, I often like to have no sign of weaponry on me, including a mundane folding knife with the visible clip in the pocket. The fixed blade, concealed under a shirt, is invisible (again, check legalities on concealed fixed blades, I use only folders when in places that prohibit fixed blade carry).
Wanting the fixed blade option, I gravitated immediately to the Ka Bar TDI. At the time of this writing, this is actually a well-established knife design, and rightly so. A few years ago someone might look at it and shake their head. Now, the merits of the design are rather well known. I find the TDI offers significant capability in a small package, much like the Glock 26 you see pictured that the TDI backs up.
The curved handle design makes accessing and drawing the knife faster and more intuitive than grabbing a more vertical-sitting traditional fixed blade, at least for me. This curved design also makes the blade ideal for the reason it was originally designed: as a handgun retention tool. Slashing across an assailant’s arms or body to retain your handgun is accomplished more naturally with this design. In my opinion, this knife is excellent as a defensive blade for the knife carrying yet “non-knife guy” like myself. Granted, I have some basic training in knife techniques, but again, I don’t put much work into it. This being the case, the TDI design makes using it defensively more intuitive. A simple punching motion puts the blade in contact with the target, giving great strength to the blow. A punch-and-twist of this tiny blade can cause massive damage, despite how small the blade is.
The TDI works wonderfully for the non-enthusiast knife carrier. The design allows it to be drawn with either hand and it can be brought to bear with great speed. It is ideal for weapon retention. To use it defensively it works right into more intuitive hand skills. Being as short as it is in the blade, it will prove more legally acceptable than a lot of other fixed-blade alternatives. Overall, I recommend this tool for anyone looking for a small fixed blade that can ride completely concealed, cut a seat belt in an emergency, or cut an attacker off your gun.