My son is corrections officer at a federal maximum security prision and a few years ago he had to forcefully disarm an inmate that stabbed another with a homemade knife ( a shank) It was made from, of all things, the aluminum foil from chewing gum wrappers. He apparently folded, pounded, and heated it somehow and got it strong enough to do its job.
So I guess we'll have to add alum foil to the list of dangerous weapons.