I found the FTU's recent report on concealable weapons (http://LB.wnd.com/FBI-weapons.pdf) interesting, but find that it omitted a few possibilities, viz: 1. The pop-top steel lid on a can e.g., of catfood forms a sharp edge when removed. (I have a permenant scar on a finger attesting to this.) If half the disc were grasped in a cloth it could be more effective than several of the items you list. 2. Similarly, the steel lid on e.g., a tuna can forms a sharp (and flatter, and slightly more rigid) edge when removed with a can opening tool. A can opening tool can be very small, e.g., the military-style can openers, which by itself is not dangerous. Again, any piece of cloth forms a graspable handle on the resulting sharp-edged disc. 3. Even a beverage can, e.g., from a beer purchased in flight, can be ripped into a sharp edge, although the thinness of the (typically soft aluminum) metal makes this less effective than the above. 4. The large knitting (crochet) needles which I believe the TSA admits could be filed into a sharp point, producing a spike as effective as some you list. As these are typically aluminum, abrading them into a point would not be difficult. 5. It is possible that a skilled knife maker could chip a glass bottle into a knife while in the restroom, producing something comparable to the obsidian knife you list. The production process might be noisy however, unlike the above. Comment, which you will no doubt ignore: Given the facility with which weapons are improvised or concealed, it might be a better idea to stop motivating the actors, as distasteful as that might be to some in power. Although some will enjoy the Israel-like police state that foreign entanglement will otherwise drag the US into, and some -perhaps your- careers might even advance faster under such conditions. Have a nice day A. Citizen