Snappy come-backs like: "why so many purses" and "why so many shoes" solve nothing. Having several handbags is normal to Mr. and Mrs. Smith. If someones handbag collection is excessive, then the worst it can amount to is economical troubles. Being defensive about knives will only alienate you from people.
When it comes to knives, let's not kid ourselves — we're talking about weapons, at the end of the day. I mean, yes of course they're tools and that's what I use them for, but that's how people view them; especially when they are well-designed and scary-looking.
If I have a simple Mora on my belt when I'm out camping, working construction or when I'm out fishing, then no one will think twice about it. However, if I'm carrying a machete instead of an axe, then people start to wonder. I mean, seriously: who really "needs" to have a socially unacceptable tool when acceptable ones are readily available (axe etc.)? Yeah, the machete is better for certain tasks and vice versa, but using one will many times give you the "Rambo-stamp" and people will think you're a wanna-be spec-ops dude or whatnot; unless you're actually deep in the jungle somewhere.
Wearing a small tactical or otherwise threatening blade such as a Kershaw or a Spydie in an urban environment isn't perceived as necessary among "normal" people, so it makes them uncomfortable. But, I have what?: 8 or 9 Global kitchen knives hanging on the wall in my kitchen and the only responses I get for those are: "man, you're such a snob" or "wow, that's expensive" and not once does the notion of a mall ninja come up. Why? Because the knives are in their setting and they are perceived as necessary, although it's excessive to have 8 or 9, like me; but, that takes us back to the shoes- and purses question and how the only obvious danger in this case is how big a hole those blades created in my wallet (no pun intended).
During Christmas I snapped out my hair-poppin' Spyderco Caly Burgundy ZDP-189 and calmly opened my packages in the blink of an eye, without giving it much thought... until I noticed how the temperature had dropped and that the whole room was looking at me like: "OMG... was he carrying that thing all the time?!" or "where the hell did that little razor come from?!". They were both shocked by how amazingly sharp it was and the fact that such a dangerous object had been lurking among them the whole evening, without their knowledge. What had happened was that I had taken them out of their comfort zone and I don't blame them. However, a few minutes later everyone was using it to open their packages!
So, what to do?! Just get with the program, don't flash your blades in front of people who don't know anything about knives. If you do, then you're just diggin' a hole for yourself. If we need to educate them, it'll have to be one by one.