Weapon

Dean came to the barrier wall set up by Holy Church. He relied on his thermal vision to escape all the patrols and came to stop in front of the giant wall. Dean used his wings to climb the giant wall.

There was thick dust and black snow on top of the giant wall. Apparently no one had set foot in here.

"There was a patrol on the giant wall by the side of inner wall. However there isn't slightest residue of human interaction on the outer wall part. They may think that no one can climb the kilometer high wall from the outer wall..." Dean pondered for a moment: "If I reverse the reasoning then it means that there are people who could climb the giant wall in the inner wall. So they are trying to make sure that those people don't sneak in or out."

He found the 'death passage' after moment. He overlooked from the top and saw that there was a red dot in the wilderness outside the giant wall.