To me, it is a fantastic and folkloric sort of flight of fancy, that passage there. I appreciate it for that, most of all. But who had ever heard of such a thing? I live across from a graveyard. I have no fear of a strongman dwelling about behind the stone of old aunt lanette.
Try to think about the story, only in slow motion in regard to the details. Think hard about what all the things in that passage would mean in reality.
First of all, the passage implies that the man was subdued. He was subdued long enough to chained up, and imprisoned to some degree, apparently insufficiently. He flexed his bicep, too hard for the iron band. How many times was this tried? If it failed once, wouldn't they increase the security measures, like finding a prison to place him into?
Then there is the 'cutting himself with stones' thing. I am not a doctor, but I cannot imagine that such behavior would be sustainable for the sixteen hours he would be awake everyday.
What did he eat. What caused him to stay where he was, away from the living? Was it the demon within him, or was it some part of his human conscious, or sense of consciousness, that would cause him to have enough sentience to avoid most others.
The story also reminds me of the Greek idea of the minotaur, and how it lived, though I may be mistaken, I will have to review that
