Just buff SCH so that their shields are consistently good, better then ASTs. WHM really does not need too much in terms of changes, SCH is the one that got the nerf bat and needs some help. SCH is also the one built around the concept of preventing damage by being proactive, not reacting to damage intake. So logically SCH should have the strongest shields so they can proactively keep healing from needing to happen. This in turn allows for more DPS to be done by the healers.