I have not read much of this thread, just scrolled through the pictures, but what I am getting is that the OP is looking for something like a "Neck-Knife" or some other type of concealable little knife. Please correct me if I got that wrong. Some examples shown here look to be about as effective as a box cutter. Ok, that is an exaggeration.
I cannot imagine myself belting on a fixed blade everyday unless I was working on a ranch, a farm, or as a game guide . . .maybe fishing. In fact, the last time I did, I had been invited to trap alligators in South Louisiana for two weeks back in 1991.
If I am concerned that I will have to defend myself with a knife, my strategy is to not go there or do that. My around town EDC today is a Leatherman Wave.