I had a Swiss Army Knife. It disappeared on one of my trips and I thought no more of it, until a year or so later when a security official at ZRH told me he wanted to examine my bag because there was a knife in it.. After a thorough search he found the knife in the lining at the bottom where it must have been all that time. During that time the bag had been through all of the following airports, several times in some cases, without detection :
CPT/JNB/AMS/DUB/NYC/BOG/BUE/MIA/PDX/MAD/LIS/FAO/LGW/LTN/LHR/WAW/SVO/BFS/GLA/EDI/NBO/BKK/DEL/BOM/KTM/MUC/FRA and probably others I can’t remember. A bit scary, showing up ‘security’ as the mindless pointless farce that it is.
Edit : Also, YYZ, YVR, BCN, KUL, HEL, and MNL.