Just Remember any knife "designed to stab/wound/damage" will usually get backlash in court. Used to carry a ti-lite, loved the knife, pocket catch, blade was narrow, great for cardboard. But if I ever had to use it on someone for self defense, and the guy made it out alive (might happen unless he threatened my wife....) But all I can imagine in court is them showing a cold steel video of my knife.... not really good from a juries view.
I know carry spyderco, Have a few of the byrd line. Simpler looking knives, cheap to buy. And if modded to have a pocket catch, a knife out of the pocket into a hand open in .5 second is a bit scary to anyone. Not scary in court when " I have to cut a lot of cardboard boxes with one hand."
I can't get my ccw yet, (have to be 23 in missouri....) So I usually carry a dirty hard use knife (byrd, kabar folder, sometimes a fixed blade mora) in my top right pocket. And eternally in cargo pants I carry an always razor sharp crkt m21 3", for cutting food mostly. Because cleaning tape off a blade, isn't fun when you are hungry.
I will second some ideas though. A good pen. I like the big sharpies for non weapon weapons. I found at while bored that a bamboo chopstick can tear the top layer from plywood. And you can carry a set of chopsticks everywhere.
also: I had an old nokia "brick" cellphone, that I wanted to break... because... well no reason. I found out they are indestructible. I beat it against some concrete, I stood one foot one each half, while it bent over a dowel rod. Eventually decided to cut it in half, with a kukri. I can get 10 inches into half inch plywood with a kukri, I got through the outer plastic and keypad of this phone. I have no doubts that the newer non-flip nokias are just as strong.