[@IceHeart]I like this idea of corruption, as for how to lessen it, acupuncture and medicine sounds good. The medicine should be more effective and, as a consequence, somewhat more difficult to come by, so maybe start off with all of the player having a set amount at the time this begins, and having to get more when they run low or such. There can also be magical spells and priest for such cleansing duties, and certain ingredients as well. As for making a character, that'd be good to, an NPC that can maybe help the more far-gone cases, where the other treatments would begin to become less effective.

Now then, how are Demon Blades distributed and their wielders treated by the people and used by the nobles and what not. If it's a heritage system, then could one house have multiple. Maybe they are given a symbols of status and what not. Also, what do these Demon blade wielders generally do, are they soldiers in war, valuable bodyguards, assassins, etc, etc.