I carry a Pelican 2AA flashlight when I fly. It's plastic, so nobody considers it a weapon. I pretty much carry a standard PSK minus sharp things (although I've been able to carry blunt nose scissors in my FAK).

My firestarting kit got some unwanted attention a while ago, so I took a friends advice and removed most of it from my kit and replaced it with a couple of lighters and a pack of cigarettes (for some reason if you're carrying cigarettes a lighter is OK, but I have been asked why I carried a lighter if I didn't smoke). I just added more alcohol pads to the FAK to make up for the lost tinder.

I pack my FAK and PSK into pouches that then go into my carry-on, the pouches have the logo of my SAR team and a copy of my Red Cross certificates, that seems to put most guys at ease when they ask me to open them.

Not having a knife SUCKS. I feel at home anywhere as long as I have my sharp stuff. I feel naked when I fly.