Does it really matter whether he did it while he was awake or asleep? Even so, he still heals himself instantly from the scratches and Mundus' attempt to rip his chest open.
Also...does that chainsaw demon sticking it to him in the game count? Or would that just be down to part of the gameplay? Got to say, that is impressive though, having a chainsaw stabbed right through you, then getting up and carrying on like nothing happened.
However, it would make more sense for him to heal fully while he is sleeping....I wish they had bee more explanitory or consistent about that. :/
Let's look at things from a perspective ok?
What age was DMC 3 Dante - somewhere between 19-22 - correct? Which is around same age as NTDante.
Before Devil Trigger, NTDante displays very weak regeneration (as i just pointed out). Perhaps and most likely the idea of Dante healing the wounds (healing is not regen) was to show that "bad ass" healing scene.
But by doing so - it makes the character's regen inconsistent.
And i cant help but conclude his regen is very weak compared to original Dante. Scratch he had on back was really shallow (it wasnt like original Dante getting stabbed, or when NTDante was chested by Mundus).
However when Mundus chested NTDante (which was after Devil trigger awakening), he seemed to regenerate so easy a critical wound in less than a minute while in beginning he couldn't regen simple scratches over course of 2-4 hours (when he slept).
So i think it's a inconsistency, but one could argue Devil trigger awakening boosted his regeneration up by alot and i wouldn't dispute that.
But if you compared DMC 3 Dante with NTDante, DMC 3 Dante had the same regeneration without awakening devil trigger that NTDAnte received presumably from awakening Devil trigger.
EDIT:
No i dont think gameplay counts. I say this from experience because gameplay and story (character being sub group of story) are often separated.
The gameplay does not answer to or follow the rules or laws that the story layers.
And in some cases some games have some of the gameplay and story stuff go hand in hand but i think thats coincedence or is a ATTEMPT at uniting the gameplay and story i.e making the rule of story apply to gameplay and vice versa.
Assume we accept gameplay feats, then if three exploding demons in DMC3 explodes right infront of DMC3Dante - what would that say about his regeneration? It would basically make him god.
EDIT 2:
The reason why i believe (and am confident i am right about) gameplay and story is separated is because if you link them together then whenever you try to add agameplay feature then the story's rules and laws will say "Hey u cant do that! No magic! Cuz my laws say so!".