It would have been nothing if he was in pristine condition but there is a small crack in his soul that created a vulnerability within him. So the damage is more than nothing, but it still isn't a lot. He is made of much tougher stuff. He can deal with it.
The physical damage on the other hand is more than a little. His body is broken apart, crushed under the force of the explosion. He is missing more than 80% of his body part. The remaining parts of his body are just his spine, some ribs, and his skull. Even his skull is caved in. As serious as it may look, he is actually alright. He is alive and he is healing. He will recover if given time.
He was thinking about how the demons had exploded. It smells of treachery. Demons can't cause their bodies to explode unless they have physical organs that will allow for it. So unless all 12 demons with different sins, races, and features have organs that can allow them to explode or something is acting on them to cause the explosion.
