d647950c_d___Game_Guide_and_Walkthrough__BONE_CHARM_PROPERTY
[BONE CHARM NAME] Plague Affinity [USEFULNESS] A charm that is useless for those who operate in shadows, because they avoid coming into any contact with weepers. You can check it out if you prefer a more aggressive approach. [BONE CHARM PROPERTY] 
Taking damage from weepers comes with receiving additional mana points.
Bone Charms - list - Collectibles - Dishonored - Game Guide and Walkthrough
BONE CHARM PROPERTY