They could increase health pools of guardians and only allow the shield to go as high as your health is with a slightly slower charge on your shield and massively slower charge rate on your white health bar in raids. That way it will open up the use for having a healing orb style class that drops orbs on abilities they use, that only raise health and not super. This class will rely on other classes to drop regular orbs to help them use supers faster for better support heals!