Well yes, of course the jacket was big on her. He was taller, more muscular, and just had a completely different build than Nabooru. He wouldn't say she looked "silly" per se, but it was plainly obvious that she was wearing a jacket much too big for her.

"'Silly' isn't the word I would use, but..."

Nabooru wasn't being very thankful, was she? Byrne wasn't treating her like she was weak. At least not consciously. So he was a little ticked off that she thought that, but he said nothing, knowing that he would have felt the same way.

"Well, if you're going to stay out here, just take it. You can return it to me later."

He had another jacket in his dorm, so if she took a while to return it, so be it.

He was about to head off to the forest to train alone, but stayed in case Nabooru had any other protests to make.