My main problem with tieing addersting to Holos, Panhaima, and Haima, and making Pneuma more powerful is that it can cause a playstyle dissonance in which in order to deal good dps you essentially have to waste your mits and heals, cauaing you and your cohealer to suffer because you wouldn't have those mits for damage intensive sections because you needed them to deal dps.
I feel like Sage should be the healer that needs to use their heals effectively to deal dps, as well as dps in order to heal effectively. These would be my changes to give it that identity
1. Make Phlegma be 30s, if the devs are focusing on a 2 minute meta, there should be no reason for Phlegma to be disaligned a 2 minute buff windows.
2. Upon earning an Addersgal, you earn addersting as well. This makes it so you need to be effective with your addersgal, to never overcap so you can keep earning addersting, however not needing to waste it all, since it only is earned when you get a addersgal.
3. Change Pneuma to become a 2 part skill. The first part would be a powerful laser that deals 600 or 700 potency. Upon using Pneuma, you gain the oGCD ability "Pneumatic" which allows you to use a 600 or 700 potent aoe heal. "Pneumatic" will be available for 2 minutes so you gain flexibility of when you can use that heal while still being able to use Pneuma for 2 minute burst windows.