You know, I have this crazy idea about what The Nameless One's crimes were.
In the public sensorium, a sensory stone tells of a soldier on a flying ship. The ship was bombarding a nation. The soldier speaks to his superior, telling him that what they were doing was wrong. His superior tells him that the enemy deserved it for they did to their own nation. The soldier tells him that the women and children could not have been directly responsible for decisions of the state.
Then, through tears, his superior tells him that regret over this could drive a man mad. He tells him that they must feel that it was only people getting killed, not women and children.
This matches with certain other things. You are told that the Good Incarnation's regret was so strong that it was "enough to build a whole fortress". It's the kind of regret one could have only from murdering as many people as the captain of the ship did. And considering that he told you he was a cartographer, it may well be a half truth. What would a man on a ship generally do, but chart courses, and areas? And when you're doing it on a flying ship, it helps you to see the relief features.