They say that power always comes at a cost. If there was anything to be learned from this moment, it was that. There was also the lesson of 'Don't randomly stick yourself in things if it could be dangerous' but such was a lesson that most men learned, and often ignored, when it came to certain things.
So let's just stick with the power one.
Like an egg constantly being injected with more and more liquid, the shell that the spirit was possessing cracked and crumbled as his radiant soul filled it with more energy than it could possibly handle, even with its upgrades.
While that energy resulted in overwhelming strength, displays of that strength weren't enough to stop the destruction of the earthly vessel.
By the time the group were stopping to make camp, not even a full hour later, the cracks had spread to such a serious degree that even the most oblivious onlooker would have an impossible time being ignorant of them.