I’ve heard of those.
Lead in the metal would seal it. Werewolves hate silver the metal but also lead, metal colour.
Some tombs had locks on the inside, could’ve been vampires or more likely occult rituals involving blood (the Freemasons fixate on keys).
Mediums would also chain themselves at particular lengths to avoid hurting anyone while possessed.
Obviously most possessed people do not do this, but a medium can force them out as well.