Maybe because they aren't potentially lethal? "Weapon" doesn't SEEM to have a definition.
I have a daughter. I tell her, "911 is what you dial after you're raped. 1911 is what you should have before they try."
BATFE, the F is for firearms. They are not the general authority on all weapons. That being said, I would recommend against stirring the pot on this one. You may not like the next rule they make up.