He uses his power to rob them of their limbs. for his ex, he coerces her into recording a certified confession that admits the wrong doings of the party. then he gets her to fall under a subordination and turn into a magic beast where she was commanded to kill the demon lord's army remnants. at the end when all of the demon lord's army remnants are defeated she is hunted like a monster and forced to run away unable to communicate that she was human, living the rest of her days as an ugly beast. The hero loses his arm. gets it replaced with a artificial arm made of light. like how our main character gained the power of darkness and probably some avatar spirit of darkness, so will the hero. Final battle, hero loses again and also turned into a magic beast where he is paraded as an monster to be tortured forever unable to die. After defeating the hero, the main character is starting to heal from the cursed chains that is causing his physical body's deteriorated state and living in peace in the countryside with two girls