From an article about property stolen from air passengers: "The takeaway: Knitting needles and ice skates are welcome on board planes, but not sparklers, nunchucks or fake chain saws."
These are not rules that any rational person can anticipate. They are ad-hoc rules that are not based on what a weapon is, but on what the TSA can get away with.
Also, this article is yet another example of puppet journalism (the bureaucrat-media complex?). I saw 4 identical headlines in my news feed in one day, with links to see all related articles. There are dozens of them. Here's how it works. A state agency, such as the TSA, issues a press release to all of the mainstream media outlets. Each media outlet reprints the press release, sometimes with local details (like a stat for how many things were confiscated at the local airport this year), and with no critical thinking. Thus, the bureaucrat's message gets out - in a big way, since every local and national affiliate Carries the story within days of each other - and any alternative presentations are marginalized to the non-professional, alternative media.
In this case, we are led to believe that the TSA is doing a good job - even protecting airline passengers - because it has so many real and fake weapons that have been taken from passengers. Nevermind that none of these passengers are terrorists, and almost all of them are mentally stable, well-intentioned, non-criminals (in the true sense of that word).
Remember this lazy journalism solidarity with the state next time you you hear about anything you're benevolent government has done. Particularly when foreign nationals' lives are being targeted by the US military.