SE has Multiple types of healing they could use

[P0W3RK1D]

(Emphasis mine)
Because you seem to be broadly breaking things down into preemptive healing and post damage pure healing. I don't see how simply flavoring why you put the healing skill before or after the damage changes all that much.
Dot 1 1 1 1 heal
Vs
Dot 1 1 1 shield 1

Hey, not all of these listed types are perfect, they are ideas, and with more indepth care and tweaking they could be viable ideas. And the diffrence betweene a pure heal and a shield? Iddoknow, ask SQUENIX, weve been using them for a while now, they love it so much they even gave BOTH to AST.
But i think a way to differentiate them would be....
Hows about Shields become a CHANNEL ability. The healer would need to select a target and cast the spell -- the selected ally would then be granted a shield, that shield will last a long as the healer is channeling it -- and when the shielded ally takes damage, instead of them loosing health, the one who is channeling the shield looses mana, the shield would break when either the caster is out of mana, the caster's channel is broken, or the one receiving the shield moves too far away from the caster.