"Carrying, displaying or discharging fireworks, guns, slingshots, or any type of firearm or weapon is strictly prohibited."
OK, so you wouldn't want to carry openly anyway; there's no way anyone would know whether you were carrying concealed unless you opened up your moth when there was no reason to.
Displaying? Only to known and reliable friends in the privacy of your own apartment shouldn't be a problem because, one again, who's to know?
Discharging? I wouldn't want to live in any building where I had to discharge by personal defense gun to stay alive. So leaving wouldn't cause me the slightest problem.
If they meant possession, then they've got a problem and need to learn the English language, because there doesn't seem to be a single word addressing that question here.
Ken