I think carrying a weapon mean you will actually resort to it when the situation demands it. For me that means that I, or some innocent person, is under the immediate threat of deadly violence or significan bodily harm. The best means of defense is of course to avoid or deflect the situation in the first place, but sometimes this isn’t possible. It only makes sense then to maximize one’s chances of surviving. If a person is trained in martial arts, that is a help but doesn’t mean you will have a sufficient advantage. Having a knife for defense is also better than nothing, but without training, or in the wrong situation is not the best choice either.
As an example, I am a big guy, but I’m also seventy-five and am dealing with a serious health issue that degrades my physical abilities. If I was to be confronted by one younger man, or two, or three and threatened with deadly force, reaching for my Yojimbo would not be a really good move. Especially if my potential assailants reached for their Yojimbo, baseball bats or guns. I think the only realistic scenario, should one want to be able to protect oneself from this kind of incident, is to carry an adequate firearm, train and learn to handle it safely and commit to the awful prospect of having to resort to it when absolutely necessary. I’d say the number of people who train adequately to deal with these kinds of threats are few indeed.
Certainly, if one of my children were present at such a time I would definitely want to maximize my potential for sudden and effective violence to protect them. In my opinion, carrying a knife, even ones like the Yojimbo or Street Beat is not the answer. Unless you are perhaps Fred Perrin or Michael Janich.
What doesn’t kill you will make you stronger. Except infantry. Infantry will kill you.
“Gentlemen, bring out your men.” — T. J. Jackson, Second Manassas, 1862