Nah man, i think MC would have (kinda easily) beat her if he went all out from the beginning. But he has the Son Goku curse and does the thing where he only "transforms" gradually during the fight (his eyes get blue or red and so on), he didnt even used lasereyes or something.
There's literally no indication that he didn't go all out and he hasn't used the laser eyes since the beginning of the game and rellies way more on wind magic. Imo this is a bunch of cope, he get knocked flying early on in the start and onyx gets disable then literally gets a fatal wound that he only managed to survived because he absored the heal crystals then after getting back up he gets frozen into a solid block of ice.
The dude lost and there was no real indication that he was ever holding back. Mc literally says in his own words that Diana is stronger than he is. The whole point of the character is that she's supposed to be around his level so after this arc is done he gets a powerful ally/sparing partner since he outclasses everyone else in his circle.
Rin is not super deep but imo has more potential and backstory than 98& of the LI's and shes not in the capital in the first place because of the mc, shes there because of her ninja thing and just got distracted by the knowledge of mc being there.
She only left her village and joined the assasain group because it gave her a chance to travel and look for the mc again. Idk imo I'm not really interested in Rin at all. She's the same as the other LI if not worse.
Did not he win but over-exhausted himself so passed out and almost drowned? Am I misremembering that scene? Why do everybody says he lost?
Because he did lost. Like I said above she delivers a fatal blow to him twice and he only gets back up because of his regen abilities and even then he was out for a good 30 seconds each time. Then in the final bout they knock each other out.
Essentially he lost twice and then had a managed to get a draw in the last round.