Well, we now know what a wizard can do, at least, one that is living in a remote village and probably retired. Perhaps ones in cities might be considerably more powerful. It's definitely very impressive, considering he's an old man but still been holding an entire groups of bandit at bay, and would be more effective if there wasn't a river around.
I don't know about having the log as a horn. XD Since Turner always has a log, Mr Dubble might start suspecting her of being able to use magic. If there are tests for magic, once it's apparent she's not the one who can use magic, they might start looking for someone else. Although perhaps Ren could make up another story that Turner befriended some tree monster in the woods?
And I guess that Ren isn't limited to enhancement magic and wind magic, he can also use wood magic, and perhaps much more. I wonder if there's healing magic he could use, since it would be quite useful here. I guess the bandits will be dealt with by Ren after all.