If I'm asked why I carry a knife, my response will vary a bit, depending on who asks the question, why they're asking and if they seem apprehensive.
I suppose the answer that I most like to give goes something like this: Take a look at this watch. It's not a quartz, it's an automatic. What's that? It's a watch that is powered by the movement of my wrist. There's a very precisely machined and polished weight inside it that spins whenever I move my wrist, and that winds a spring, which powers the watch. It's a high precision time instrument, that is beautiful, in my opinion, it's manly, and it keeps great time, too. It's part of who I am, and symbolizes much about me.
Then I'll pull a really nice pen out of my jacket, and show it to them. Check this out... it's beautiful. And it's a very high quality writing instrument, that feels great in my hand, looks good, and writes smoothly, with beautiful blue ink. This pen says a lot about me, and symbolizes elements of my personality.
After that, out comes (if it isn't already out) my penknife, which in my opinion, is a work of art. I'll show it to them. And say something like, check out the quality of its construction. It is so smooth. It's machined to very high tolerances. It has a ball bearing pivot that's silent. It's so slim I almost don't feel it in my pocket. And it'll help me open those Tyvek envelopes, or cardboard boxes, or cut string, and a thousand other pesky items. It was designed by a top custom knife maker named Ken Onion. He's really an artist. And so I'm carrying a piece of art that is also functional, like the watch and the pen. This little penknife makes life a whole lot easier.
After this explanation, if they're not bored to death, they'll want to check out the knife, and put it to use. Just for cutting paper or ads out of the newspaper or magazines it's great.
Thanks for reading.
P.S. If the question is coming from a guy who's not apprehensive at all, I might just tell him I use it to trim really good cigars. Nuff said.