I love the sense of safety the knife brings. I also love to flip it around in my hands when I'm idle. If I ever go anywhere without at least one blade attached to each on of my pockets, I feel naked. I'm also probably biased because I've practically have had a blade in my hand since I was a baby... so maybe that's behind my sense of nakedness when I'm not wielding. The knife is simple to conceal, and simple to use in many different ways. It is merely an attachment to my fists, and with that becomes more deadly than a thug slashing away without technique.
I suppose they are also good for opening boxes and envelopes...

Kol Tuv.