I fully believe Mr. Faust is the most disturbing part of malevolent. By a long shot.
It’s not just the idea of cannibalism or murder or Arthur’s barbarity caused by tkiy that makes it so disturbing. It’s John that makes it so disturbing. It’s Arthur’s ability to see the death of corpses he touches. The fact that every single time Arthur touched Faust to take a bite of him, John had to watch his death over and over just so Arthur could eat. A constant reminder that the worst, most powerful parts of John caused this, and that in a way, Arthur’s violence was his fault. It’s like the king is telling John that he can’t escape what he comes from, his true nature.
And whenever Arthur does his corpse touching ability, it sounds like it hurts John by the way he talks. So what was he doing while Arthur ate Faust? Was he silent? Was he begging Arthur to stop? Stopping means starvation. This is why Faust is the ultimate punishment to me because it effectively dehumanizes Arthur and destroys John’s self image and faith in his friend, which are key parts of their individual characters.