I’m pretty sure the meaning isn’t that you aren’t allowed to turn an ordinary item into a weapon. It’s that you can weaponize ordinary items. If you make a pipe bomb, for example, it’s pretty obviously a bomb now, and not an ordinary pipe. Basically, making it so people have to fear using ordinary items is what we typically call terrorism.

I don’t like that word, because it’s usually just used as a weapon against less conventional forces by states with more power, meanwhile the states typically still use fear to enforce a political agenda. In this case it’s unarguably the bad kind of terrorism, and they should be held responsible for it.