No Weapons are allowed

This was a sign at the entrance of a street fair. Who are they trying to convey this message to?

Ordinary people like you and me, don't have weapons.

And for those who carry weapons (cops excluded), are they really going to leave their guns/knives/pepper spray in their cars after reading this sign? I doubt that.

Besides, what's the definition of weapons? We all know it is not necessary to have a physical object to harm someone.