I immediately thought of Warhammer: Age of Reckoning's "Disciple of Kaine". It was an experiment with a "melee" healer who built blood gauge by engaging in melee combat then expended that gauge with heals. They did something similar with on the other side of the faction war with the War Priest as well. Was an interesting concept that I haven't seen explored enough.

So many healers spend time on the back line, it would be nice more of them on the front lines again.