JKSManga
I remember how Vincent told him all those chapters ago that the only way to learn skills was either to spend the skill points or to find a teacher, I feel like either Arthur will die at some point in the next fight or he will act as a teacher for the shadow abilities. If its the later I forsee a merge of the 2 castles, the 10th castle where Quinn is the leader of and the 14th Castle which used to belong to the punishers.