Defender is in a good spot right now. They allow an over shield, one body-shot snipers to exist, and can shut down supers. The bubble is easy to pop with another super, so everything else I typed makes it as balanced as it can be. The super already got a nerf, so it should be left the way it is. Let Defender be a high risk/high reward subclass, it is the only super that doesn't get instant kills, but can buff the entire team you are playing with. This makes it very useful in all activities if used by a high skill player, and can make for awesome plays and saves.