Oh, that? I had to fight a sexy evil mage once and considering that we didn't have time for me to do the standard training arc...

[It required dragging out some of the potential that Nagi already had within him. It looked like a lot of his training required him doing some fast level grinding depending on the situation at hand. A similar incident happened whenever he had to get a bit stronger in order to obtain Judecca.]

I had to get the crap beaten out of me to learn a proper spell. What didn't kill me ended up making me loads stronger.