I think play testing these proposed changes in isolation from one another would be a good idea but. When we are talking about closing the gap between heavily armoured fighters and light armoured fighters i don't think proper consideration has been given to damage mitigation beyond the ap value. Namely avoidance. Someone in as much armour as i wear is taking every single hit he does not block with shield or boffer. A light armoured fighter has another option of dodging or simply running. From that stand point i feel like heavy armour should always be significantly better then light as it essentially robs you of one method of defense. I think the proposed change to armour smithing may be enough. The new breach mechanic seems unduly harsh on heavy armour. In a wave battle for instance which deals with the desired attrition style combat one destroy armour or a last second slay while withdrawing now halves the ap advantage of the armour while it retains its hefty negative to avoidance. When a heavy fighter breaches in a battle like that he is a corpse. The light fighter can still run and live.
Elderly Human man wearing a long grey coat over chainmaille.