"<Heal> which can barely heal a wound"
But I remember the early chapters having his heal even curing status ailments that no other healer can do. It's exactly why his last party was so disappointed in Laila as a healer, even though she's supposed to be a competent healing specialist like she does outside of that bad party.
"A talent that can't even be called a talent"
So he IS talented, just not in the way others would want to acknowledge. If what he does is impossible to be replicated by anyone else due to something special about him then it is a talent; if others can do it too then it's a matter of technique... a "skill issue" they'd say.
That the mechanics behind his power is only being explained in ch.25 is kinda ridiculous. So he's apparently paying a price for the power he shows, since he isn't using the typical game-like "Skills" but doing things closer to how beings without "Skills" do, like elves? He's damaging his body for this? Then I guess that's where the healer part comes in, and he uses his only Skill Healing on himself?