A demon curse. They're what we had to turn to, to keep up with the times. Powerful demons sealed in sacred items, like a weapon. Just touching them is enough of a risk to lose yourself to their temptations completely. If the demon takes over, you'll become a man-eating monster and go on a rampage.

( Steady, matter-of-fact, textbook. )

But if you make it past that, you can use their power to far surpass the strength of a human. Severed limbs can reattach, organs can regrow. By feeding it more desire, you gain more power, at the risk of your own humanity.