Zuko creased his brow and opened his mouth to verbally retalitate when he realized that...she was right and promptly shut it. She was right, he could fight without firebending. Hell, he hadn't firebent once while masquerading around as the Blue Spirit (even though he only did so out of fear his fire would give away his identity), and aside from the caves, had fought in Ba Sing Se only using his swords.
If there was one thing he was and Azula wasn't, it was a master swordsman.
Katara was right.
"I'm an idiot," he admitted suddenly, a light smile playing upon his lips as he shook his head. Then jokingly, "The lack of sunlight must be killing off brain cells."