Dark Moon
The moment Gabriel pointed out he was laughing like a maniac, Nero stopped, feeling a little embarrassed at his display. The main reason he had gotten carried away was just because he learned something new that was also very useful, but also because it did not use up a lot of his aether!
Sure, covering his body with aether to use it as defence actually ate up a lot of aether, but only when it was actively defending against something, such as the effects of the red sand. Otherwise, it barely used up any aether at all, because Nero could just pull it back into his body.