[He frowns as he watches Katara move, a brow slowly rising as he notices water gathering above her hand. When he sees the grass crumble into itself, his eyes immediately go back to where she had started replanting.]

You pulled all of the water right out of it. [...It's definitely useful. And extremely dangerous, if it's something she was able to do this easily. There's a faint wariness as he continues.] I hope you at least won your spar, if you had to do something like that.