Treating tweezers as a viable hijack weapon simply screams the government's obtuseness about aircraft security. Go ahead, try to imagine a scenario in which you could use tweezers to keep 200-plus passengers at bay while forcing the pilot to do what you want.
....Yes, there should still be a list of banned items, but the ban should stop at this bright line: The item is not only potentially dangerous but also dangerous to more than one person at a time and obviously so. Even though a pair of glasses can be used to perforate someone's trachea, a crowd of passengers would take some convincing of this, and even if a would-be hijacker used them this way on one person, he couldn't then hold off a planeload of people with them. On this approach, automatic weapons would still be out, but tweezers would be back in.