Second Eye
"The more brutal the oppression was, the more intense the resistance would be. When a riot led purely by the witches arose, how much damage would that cause to the Kingdom of Graycastle? The hatred caused by the church, once uncontrollable, could very likely be transferred to the same hate toward the kingdom and its people" I've heard Abraham Lincoln had a similar line of thinking when he decided to abolish the slavery.
"If we want to develop Nana's power before the Months of Demons, we can't conceal her identity as a witch" err, no? You could, for exampe, say she was a saint? It was even hinted to him by the knight, Brian, but nooo! The MC had to fish for troubles and correct him, snitching the witch out. But I guess there would be no immediate conflict with the church that way, losing the interest of the war-focused readers...