My vote would be a two or three layer 91mm SAK. Cheap, easily replaceable, useful other tools, very friendly looking. If you want locking, a couple of the wegner evo knives have locks, in that size. I've carried little knives, and I feel like you get more utility out of a SAK than out of a single blade at that size.
If you want a single locker, Take a look at Buck, they have a couple that fall under your requirements, like the knight, prince, 55 or colleague.
If you want to be silly, a SOG flash 1 is the right size (but might get you in trouble anyway).
The leatherman juice line lists the main blade a tenth of an inch over your limit, but thats another option as well, (I'd ask first) but that puts a bigger set of pliers in your pocket, as well as some other useful tools.
Over all I would avoid anything that looks too tactical or flashy. Stuff that says "my grandpa gave me this" goes a lot farther towards a warning, or a caution over a seizure and a record.
For a light, look at the Fenix E01, and E05. great little 1AAA lights.