Mention the carrying of a knife, and people snicker as if it's only Jack Bauer and Jason Bourne who have the wherewithal to use a knife for personal protection. Mention that there are non-fictional individuals who carry knives on a regular basis, and the same people will look to make some "witty" and disparaging remark on the matter, e.g. "What neighborhood do they live in?"
If you mistake these folks for open-minded people and mention that you sometimes prefer to go armed, you won't hear any commentary at all ... but they'll suddenly recall that they have somwhere else to be, e.g. "Excuse me but my teenage daughter is being fitted for a diaphragm today. Gotta be there to make sure it stays in place."
Where does this pathological blade phobia come from? There was a blade present at your birth. There was a blade present at your circumcision. There was a blade present at your first -- and subsequent -- haircuts. You use a blade to eat, shave, cut paper, and groom your nails. A doctor will use a blade in the most basic types of surgery, and the embalmer will ... well, you get the idea. Why then, does society seek to be so disconnected from something that is so fundamentally inextricable from our lives? Possibly because in this, as in many other areas, it is a disconnected society. Ironically, it is a society that is cut off from reality.
Some day, when it's much too late, these people will realize -- as many among them already do -- that it's better to have a knife and not need it than to ...
Keep your friends sharp, and stay away from the dull-witted.