you know man I have been looking into it for a while and it seems like its just it is only illegal to conceal fixed blades, autos and balisongs. but at the same time the wording is hard for me to understand. I have been looking at charges that have been filed in nc and concealing a switchblade or any weapon AROUND or ON your person will net you a charge.
but iv lived in nc all my life and any manual (or assisted) folding knife is fine for sure. Just inform the officer of your knife when they ask if you have anything that will hurt them and you should escape with your knife intact. In my few run-ins with the police i handed them my knife and he handed it back to me. Any knife in government buildings can get you into trouble and its a felony to have any knife on school grounds or while participating in a school sponsored trip or activity in NC
I am positive that on a belt sheath is considered open carry, not sure about clipped to the top of the pocket though. I saw a cop explain on a forum that if he can see the knife when he interacts with you it is not considered concealed.
NC is pretty conservative, we like our guns here, so a typical folding knife wont be a problem. Just depends on what you are doing with it.