"If it will help me achieve my aim, I don't mind it."
The changes to his body and his sin are the positive side of things. These positive aspects of his existence are due to the influence of chaos. The negative sides are also due to chaos. For starters, his soul almost crumbled. The current power of his soul is almost nonexistent. It goes to prove how close to death he was. Thankfully he has begun to heal and his soul is growing stronger.
His sin of chaos might be great but he has also lost access to mana and magic. Demons may not be able to access laws, but they have a way to enhance mana into some sort of transcendent energy that can match Origin energy in power. But now, he doesn't even have access to it because of his chaotic energy. His chaotic energy is all he has and what he has to rely on if he intends to achieve his aim.
"Let's see what this Chaos vessel is all about."
