One time I was in a hurry and had forgotten that I had a very valuable foldable knife in my backpack when leaving for a flight, and with no time to spare I had to let them just take it.

At the destination curiosity took over and I had to ask a security guard if it was possible to get it back when I returned, something he confirmed. They handed valuables like that over to lost and found.

This naturally made my day a little better and I didn't think much about it until a few days later when my return flight was. I went to the lost and found, no dice. I asked some security personell on site, and they confirmed the practice, all valuables, including knives, was sent to lost and found, where they logged it and kept it for a month or so.

So the guy who was going to protect us all from terrorist attacks had just stolen it. Reassuring!