

While Jin's One-Winged Angel form is very strong, it's nowhere near as powerful as Bloodlusted Mythra, let alone Pneuma. Mythra was also holding back a lot of power due to how much destruction she caused during her Unstoppable Rage against Malos, and she couldn't go use that power because that was tacked onto to Pneuma's sword and her powers, which was sealed in the Spirit Crucible Elpys. It's pretty obvious why they needed Pneuma for him at that point. However Torna: The Golden Country reveals that Jin is the Paragon of Torna which makes him one of the strongest Blades around, then he gets a One-Winged Angel form due to being a Flesh Eater.


