[He doesn't see the issue with this. He didn't use it because he wanted to show off, he used it because he truly thought it was needed just to be able to fight his opponent. Though Aether's right, he had pushed it. And he's not even telling him how many times he's already had to use it while he's been here.]

Come now! Aether, you know I can't promise you that.

[He gives his friend the look- he knows the one- his eyes wide, almost begging for him to reconsider.]

For as long as there are battles that exist to test my limits, I will use the transformation to become stronger still. Believe me when I say that I didn't use it lightly. This world contains an unbelievable number of individuals that posses a strength that I could only imagine in my wildest dreams!

[Childe sounds like he's gotten the keys to the candy store and he's frolicking about in it. Reverein has everything he could of asked for.]