2.5"?????? That's not a knife! I have wooden toothpicks bigger than that!
There are many high quality small bladed knives (although I don't know why) out there.
Your best bet is a Gerber Nautilus. The knife blade is slightly less than 2-1/2", it has both flathead and phillips screwdrivers, good scissors, a great grip, and best of all a great working LED flashlight and laser pointer built right in. It's great for finding the right key or door lock in the dark, and it's bright enough to light a walking path. It's all in a package no bigger than a Buck 110. Outstanding! I love mine (I have several of them). Since it has tools on it, and a belt-pouch, I believe Law Enforcement would be a bit more lenient on you with one of these, and would consider it more as a multi-tool than a weapon.
Semper Fi!