Cane: I carry one, well walk with one, all the time. I'm 16 (look 18 or 19, not that it matters much, and I dont get to many funny looks. beyond first glance I'm just another cripple,(No offence to those who are, I have my walking troubles [bad knees] too, so this isnt a "dig" at anyone) just a little younger than anyone else.
G-10/Carbon Fiber knives: My Girlfriend carries a g-10 neck knife, that I made. I carried it a little before she claimed it. Its plaine dge, but in my experiments if you put full serrations on one it will cut like mad. Hell-uv-a stabber as it is. Even as non-metallic wouldnt make it through an airport check point.
Solid, heavy duty writing instrument: Dont own any really solid pens, or mechanical pencils, but a Sharpy marker should make a hell of a kubaton. Not as solid as a metal one, but then again humans arent as hard as walls, so its not like you're gonna be pounding it into a rock cliff face.
Flashlights: I dont think you could get a big Mag-light onto a plane. But they are still a good thing to have and to hang onto. I keep one (3-D-Cell) next to my bed (altho I havent used it lately, I like a smaller flash-light for in the house, unless I thought I was gonna need to hit someone with it). A mini-mag light, or a smaller Sure-fire (gotta get one of those) would make a nice impact weapon/pocket stick.
Clothing: Someone mentioned their belt. I think I could hurt someone with a solid leather belt, especially if I had one of my big show buckles on it.
Boots. Pointy toed cowboy boot to the shin isnt fatal, but to an attacker who isnt on PCP or Crank, or similar, it could mean those few seconds in your favor that allow you to get the upper hand. Even work boots, or biker books, are a heck of a lot tougher than sandals or tennies or dress shoes.
Strong shoe laces. Maybe I'm nuts, but if you had the time to get a shoe lace off your shoe you might be able to use it for a garrote (depiration makes ppl capable of some amazing stuff.)
Bandana, lot of people have done things with the bandana, look at the JSP Bandando, and didnt keating do something on Bandana use? I havent ever looked into it, but I think it would be worth looking into.
Watches: Given this some thought lately, since I have started wearing a watch. You could put one to some use, with a little thought, back-handing, and punching with it. Might hurt like hell for you, but if it gives you a couple seconds to grab somethign and do worse damage to a would be attacker, and thus keeps you breathing, a little pain was worth it.
Thermose/Insulated Coffe Mug: I see more and more people walking around with these all the time. And a good number of them are made with a stainles steel shell. And some are quite heavy. A hard blow upside the head from one of these would HURT. A hard blow to the temple, might do worse. Again wouldnt count on it to be fatal, but if it slows them down some....worth a second or even third thought.
Breifcase: I own a Samsonite breifcase, with an aluminium body, and leather cover over that. its got some weight to it, but if you could swing it, a blow to the head, or to the hand of an attacker holding a weapon, has the possibility of being effective as well.
If nothing else, hold it with both hands, and smash it down atop his head, shorten his spine a little.
Hand Bag: For the women, or the guys who realize how much easier it is to tote around all our junque(junk) if we have a bag with a shoulder strap. Mine is small, made from tan cordura, main pocket, small middle pocket, outside pocket, all with zippers, and then a flap over the top. With various stuff in it, pens, palm top (I dont have one, just guessing about othe rstuff) watches, multi tool maybe, pack of cigs (again no I, just guess), or for the ladies, we all know all the stuff they carry aroudn with them.
Not a bad little flail, has some weight to it. Not a main weapon, but enough distraction to draw something else (just as long as it isnt in the bag).
Sit down, and just think about this stuff for a little while....you'll come up with some ideas of your own.
The human mind is a very devious device. Put it to use.