I’ve just realised why I love the Final Agni Kai so much (and why it’s the best fight in Avatar). They are both fighting like each other.
Zuko is confident and at peace with himself. His firebending is the best it has ever been and Azula is unhinged. So he stays on the defensive, exploits her weaknesses and exploits her unhinged mentality by antagonising her into fighting on his terms (e.g. “No lighting today?”) and making her do what he wants.
But Azula is fighting like Zuko. She is constantly on the offensive and driven by rage and a desperate need to prove herself. She’s caving under her family issues, feelings of abandonment and the slights that have been made on her honour. Because of this, she is blind to Zuko’s actions and can only focus on giving the battle her all and proving herself to her father. Hence why she falls for Zuko’s trap (e.g. “I’ll show you lightning!”)
I just love this show, and I find even more reasons to love it every day.