Clemency (in combination with the trait Divine Magic Mastery) makes you able to heal pretty decent. At the moment I can heal back to back 5 times with a full mp pool, each heal healing between 11,5k and 12k. This is without being in any group and without convalescence or requiescat. You get Clemency at 58 and Divine Magic Mastery at 64. Before that, you shouldn't really need much healing, you're already more tanky then other classes. And in dungeon there's a healer to do that job for you.