If society as a whole is breaking down, screw concealment and subtlety. If I need to use my knife as a weapon, it better be the biggest, ugliest, most intimidating piece of steel at hand. If I can't even get out of the area with my gear, all else is moot. Dogfather all the way. Big knives can do small knife work, if awkwardly, but you're not going to intimidate anybody with by pulling out a small knife.