[@IceHeart]

Good ideas, but how about the Demon blades Origins and distribution. Maybe they have demons sealed within them, which could translate into some form of sentience as well, though how much could be keft up to the player or you. Another angle is that they've been forged by or with the assistance of Demons, maybe even made originally ti fight demons before becoming corrupted by the demonic influence of their blood after so many years. Also, you mentioned how the blades also curse the wielder, maybe their should be some sort of cost to using ones ability, like blood, pieces of one soul, or maybe they have to perform certain actions as payment for the power, like having to kill someone before they put away the sword or something else of that nature.

For the experiments Idea, I ask how far should we take these abilities, what the limits should be, and whether we should have so they have one main ability, and everything else brancjes out from that, or they just have a bunch of different abilities to give them some variety.