Walking through the alleys of the docks district of town, you hear an old, mad beggar calling out for alms. He claims to be a god, cast out from heaven and stripped of his powers. The party passes, tossing a few coppers to him. In thanking them, the madman refers to incidents in their childhood or distant past which would have been all but impossible for him to know.
A certain country allows most civilians to carry weapons, but only if they are potentially deadly. Pepper sprays, stun guns/tasers, batons, and dart guns are banned. And if you kill someone and are not acquitted at trial, the punishment is to be hanged the day after you were found guilty. The message here is that if you want to go armed, you had better be prepared to risk killing someone and being executed unless it was clearly self defense.
When it comes to combat spells, again, only the highly dangerous can legally be cast with the same possible consequences if cast wrongly.