One other specialist NPC role that the Mediumship talent can be used for are
Sin-Eaters. These are people who are called to take on the sins of the newly dead, in order for those souls to move on to the afterlife. Sin-eaters are typically from low "untouchable" social classes. The gaming use of such an NPC would be to prevent someone from rising as a ghost, wight, or other kind of restless undead. Sin-eaters wouldn't be able to prevent conversion into a vampire, werewolf, or zombie, however.