Then we get light novel Naofumi, who spends most of the early story being so mentally broken he's almost completely given into being everything he was accused of, to the point he genuinely bought Raphtalia with plans to use and abuse her as a stand-in for his boiling hatred towards Malty and the entire female gender.

He still has enough morals left to empathize with her traumatic life and decide to not abuse her, and he gradually improves in both sanity and morals over time, but the fact remains that novel Naofumi is so mentally and morally broken, it makes manga Naofumi look like the anime version.

Agreed, one of the worst parts of the manga/anime difference with shield hero is this

:
ANIME SHIELD HERO: instantly becomes a morally white hero filled with righteousness. Protects the girl that wronged him from being executed.
MANGA SHIELD HERO: Resentful and still with trust issues, Actually asked to execute the girl that wronged him and only didn't happen because the queen stopped him and told him to choose another punishment

I'm not gonna bother watching season 2 sorry, naofumi is a morally white empty character in the anime that gives me 0 interest when we have shows like Attack on Titan right now with so many well develop characters in morally grey thought provoking areas