Oswald's a genuinely talented mage—capable of wielding all four classical elements, which is legitimately impressive. He's actually more skilled with them than Edwin is, though that's not saying everything about his character.
The turning point in his arc comes courtesy of Yumiella, who basically humiliated him by obliterating a training dummy that he'd only managed to dent. It was a brutal reminder of the gap between them, and he took it hard—hard enough to swear revenge and nurse a serious inferiority complex. Fans note that this moment defines his early motivations.
What's interesting is that his grudge doesn't stick around. As the story unfolds, his resentment toward Yumiella gradually fades away. It's one of those character arcs where initial bitterness gives way to something more nuanced, though the specifics of how that shift happens shapes a lot of his development.
Content compiled by AnimeList.moe from publicly available sources.
