Re: how many blades do you use?
Having been caught in enough situations where I wish I had a sharp edge and didn't, I now carry enough to suit me in any situation.
In my pocket, I carry a Cold Steel Voyager. My only complaint with this knife is that the handle is not as strong and useful as a steel handle. My last carry knife was a Kershaw VaporII, which just weighed my pocket down too much, so I traded it in for a Zytel handle knife which only weighs a few ounces even with a heavy 3.5" blade.
The tanto point ensures a long straight cutting edge, and a strong tip. I use
it for everything: Cutting, prying, as a screwdriver, as a hammer, etc. The handle's not let me down yet, so I don't mind its "plastic" nature. I also like the lockback, as liner locks tend to get jammed in the locked position after they wear down a while, in my experience. Even with nicer knives, like the CRKT line.
I liked it so much, I carry a Cold Steel Tuff-Lite for my keychain. It's tiny, but has the same nice AUS-8A steel. It doens't have stellar edge-holding capability, but it hasn't snapped on my, so I like it fine. I've had both for over year now, sharpening once and a while to keep happy.
I use the smaller one for delicate jobs, so it stays super sharp. Like if I don't have scissors, it'll cut paper no problem, as well as envelopes, even hangnails when I can't find clippers. It's also nice to have when I'm in a setting where my Voyager is a little inappropriate (people aren't always comfortable with larger blades out in the open).
Finally, I've carried a regular old 10 cent razor blade in my wallet in a custom "sheath" made of index card and masking tape. It's thin and I don't notice it in there, and it's great when you've forgotten everything but your wallet.
In addition, I have a few straight sections of hairpin in my wallet. You'd be surprised how often you need a small thin piece of metal. I once one when a friend realized he'd forgotten his bolt lock on his Remington out in the field.
Finally, I have a Swisstool multitool on my keychain. The 420 steel's nothing too impressive, but without too much weight the pliers are incredibly handy, as are the 4 screwdrivers on there, and wire cutters underneath the plier jaws.
I was never in boy scouts, just find myself using these things all the time!
I highly reccomend the Voyager. You can't feel it there, but if need be it's still tough enough to fend off somebody threatening.
"The distance between insanity and genius is measured only by success."