It's a pretty typical anime/video game trope for a heroic character to have that last desperate surge of strength despite them being at death's door seconds before. It's also a well-established fact in this game that a strong enough emotion or desire can generate power. And given that the game is, despite touching on darker themes, overall a heroic fantasy story, I don't really feel like it stands out that much.

I do wish they'd actually shown the scene of the Exarch merging with the younger G'raha. If they'd actually had some dialogue, maybe come to an understanding, made any effort to make it work, it might've helped. But with 5.3 running long already, I guess they decided that had to hit the chopping block.