The Pope struggles as explosions on the ship continues to engulf the whole thing. Seeing that almost every soldier that were trying to salvage the ship have either jumped off the water or have died from the blast, there is no more reason to keep hiding what he was hiding if his life is on the line. He might have divinity blood but he wasn't recognized and worshipped as one which is why he is still considered as half divine. He will still die in the process upon receiving a lethal wound.
The burst of light that came out from his body is the divinity powers at work. He is still a god candidate even if he didn't ascend as a proper god. Using it will give him a slight boost of power and the ability to use his powers as a god temporarily but since he didn't ascend as a god he will not be able to keep using it compared to the time when he was still a God candidate. He has already passed the time limit to become a god.
