Sounds like the Chicago law could get you on the 2-1/2" blade length limit, but there may be an out based on what qualifies as "concealed".

The Illinois law specifies 3" period. I think the knife you are looking at is 3-1/2". No mention of concealed or not concealed in the Illinois law. And that other clause "...or is otherwise armed with..." sounds scary too. That may catch you with it in a car, in your backpack, etc.

I'm not a lawyer and can't give any legal advice. What I predict could happen, is that you'd stand a good chance of losing the knife to a police officer (at minimum). You may be able to get it back later. They probably wouldn't give it back to you while you were in prison though, should they decide to interpret the law in that manner! <img src="/images/graemlins/frown.gif" alt="" />