Really the only thing blocking things like this from existing en mass would be the expense in crafting them.
The concept of the behavior enforcing item can be used widely, and this is a decent version.
In many medieval settings, I don't see this device replacing the headsman's axe or other corporal punishments except for overtly 'enlightened' societies. The rich might get collars, the riff-raff get the axe and the rope.
The other comments really say what is needed here. Right now they feel like cardboard cutout villains to fill the 'burn the witch'. There is good drama potential with how they deal with heretic priests and the like. Go to Comment