Last Fall, in Toronto T2 I was refused passage through security because of the weapon I was packing. It is a "Mini-knife" with ... wait for it ... a one-half (yes, 0.5) inch blade, just over 1 centimetre. I have carried this with me for 20 years on hundreds of flights in airports all over the world; it has often been looked at and then returned with a comment like "Handy".
Not handy to T2. They wanted me to go back to checkin, check the knife (which has an overall length of 3 inches) and then come back through security. Yeah, right ... ever see the lineups at T2?? Plus, all I had was a carryon bag, so then I would have been waiting for my "luggage" at the other end.
Finally, after going up several levels of supervisors to no avail, I took the knife apart and surrendered the blade.

The best part of this is that I had already been through the same security checkpoint about an hour and a half before, then gone back to the main terminal to get something to eat. Same guys--earlier it was OK (or not noticed), later it was a dangerous weapon and not allowed. What crap! I insisted that the incident be logged.
When I was signing the incident log, I pointed out that the pen I was using was actually a more dangerous weapon than what I was surrendering, but they let me keep that.