So, Darin's got part of the soul of a demonic god in him which gives him super-human strength and resilience. He can take a lot of punishment and dish out just as much but he's spent his life avoiding the use of his power so his body has plenty of limitations. If he punches too hard he could destroy his arms from the recoil, etc. Honestly, the closest comparison I could make in FF16 terms is that he's basically always semi-primed, he just hides it.

So if Garuda and her sisters start ganging up on him, he'll hit fight-for-his-life mentality and abandon the idea of hiding his power (and he'll hate it) so Benedikta can absolutely needle him about it later. Aside from super-human strength and resilience, he's a brawler with a dao. He'd scramble to get on top of her and just start slamming with fists to try and ground her or her sisters.

Attempting to drown him would honestly be badass. Forcing him to actually use his power and get close to losing control would be some great foreshadowing for later things I can do with him.