I carry my swiss army knife (soon to be a leatherman), AA flashlight and whistle in my pocket. Noone has ever given me grief, and many of my coworkers carry knives, too.

I think someone made this point last year when the subject came up. A multi-tool is a TOOL, whereas a fixed knife is a WEAPON. Folding knives are in that grey area. That's the perception you're dealing with, and preparedness means being prepared for social bumps in the road as well.

My personal feeling is that in a typical office environment, a good multi-tool with a locking blade will be highly useful, without any social / legal risks at all.