Just some 3AM mental meanderings:
Knives are good, but a lot of people carry them, so the chances of winding up in a knife-on-knife fight are pretty good. I want to have an advantage over the guy who brings a knife to the fight.
Tomahawks, where legal and used with some skill, are hard to beat in close-in non-firearm fighting.
http://www.americantomahawk.com/tomahawk/
Edmund Rowe has pointed out the efficiency of the common entrenching tool, and carry of an e-tool isn't as 'aggressive' as carry of a tomahawk.
Walking sticks are legal everywhere, very discrete, and stick-fighting schools are becoming more and more common so getting some stick skills isn't hard.
LawDog