I guess the caveat is that security has to recognize an item as fitting one of the three criteria you list for it to be disallowed. There's actually quite a bit that you could edc that would not be immediately recognizable as a defensive aid, at least until it is used as such.

Based on my own experiences, and since I am a licensed IT specialist as well as my regular vocation, there is a whole list of tools I would claim I should be allowed to have with me regardless of where I go to work. Without them, an important aspect of the work I do could not be accomplished, and most all the facilities I've been to, even highly secure areas, will have a provision for tools of the trade. In many cases, as a minimum that means edcing a multi-tool at the least. This includes places like federal courthouses, jails and prisons, and nuclear facilities. While pepper spray or a fixed blade knife would be an obvious no-no, my LT Wave and such have never been a problem.

However, were I to go somewhere I couldn't even bring my Wave, I would get the most powerful laser pointer I could afford and bring that instead. After all, a laser pointer is a fairly common office tool. I'd also consider a double wound piece of stainless steel braided wire used as a necklace (I can't wear any jewelry that has copper or silver in it due to a serious chem reaction). I also like to carry a roll or two of quarters with me in case of emergency vending machine jonesing, and that spare pair of socks in case my feet get wet. I also prefer to keep a bottle of my favorite "Ground Zero" or "Inferno" hot sauce handy, in a convenient squeeze tube dispenser.

Hopefully you get the idea.