Armor is an aesthetic. Unless you mean it would actually have higher max HP and defenses, but that then begs the question as to why this healer would require heavy armor and HP compared to other healers--like what purpose does it serve? In FFXI, DNC could wear leather armor class and was technically a healer but it was only because they were required to build TP through autoattacks to heal (and there was no dodging aoes in FFXI), so they sustained more damage than normal compared to WHM which was a ranged healer.