I don’t keep a pocketknife or anything other than my wallet and my cell phone on me at any given time. My dad is the sort that thinks every guy on the planet should have a knife in their pocket and is always looking for an excuse to use his knife.
I have a cousin that keeps a Leatherman tool, an iPhone, and a flashlight in his pockets at any given time, which is overkill me thinks. If I were going to carry something in my pocket it would be the Guppie, this thing is cool. It has an adjustable wrench with 1/2" jaws, carabiner gate, LED light, screwdriver, and a bit carrier.
That bit carrier sticks to the side of the Guppie with two magnets. The thing also has a high-carbon stainless steel knife blade for cutting things. The Guppie is rather largish, so you will need big pockets. The handle length is 3.5" and the Guppie weighs 4.1 ounces. You can get yours for $39.95.