I carry a Swiss Army Locksmith in my pocket. It has a wood saw, metal file and saw and a larger than normal (for a Swiss Army knife) locking blade.

In my back pocket is a one hand opening lock blade, usually a Spyderco with half blade serration.

On my belt is an old Gerber BMF. I have carried this knife since about 1986 and it is still fantastic.

I have a bad habit with knives, I will deliberately try to break a knife after I get it. I will try anything short of clamping it in a vise and hitting it with a sledge hammer (although I did that once with a Cold Steel Recon Tanto, and it held up), just so my knife does not break on me when I need it most. It can be expensive though. My sheath knife is a tool, and must withstand great abuse. The Gerber BMF has done that. I even drove it into a crack in some rocks once, and hung three grown men from in a rope. I have Kabars, but they are more for sentimental value, I have broken many of them. The Tanto was strong, just not designed as a good field knife (size and shape). It took more abuse than any other knife I have ever seen, only needing a bit of sharpening afterward.