The skill combo is pretty cheat, with literal max HP it's unlikely he would ever get one-shot and being healed doesn't reduce the power (like a skill that just does damage equal to the difference between current and max HP would be), add in that he takes damage for the party and he basically makes the party invincible as long as he can get powerful enough heals regularly enough.
Not that I am complaining, I can enjoy a good power fantasy but just an assessment.