How much functional control can you get of the weather? Or is that GM controlled in some way?

I'm thinking something Red Cliff-like now. And I'd link the scene for reference but I guess no one's got to posting Kaoming's apt ability to predict the weather.

But while I'm reminded of Red Cliff... [url=https://www.youtube.com/watch?v=r-briQqhGZY]Steal his arrows?[/url]

Provided you can't manipulate the weather and still want to do this, and provided you got the opening, you could set fire to the field ahead of you, just to cloud it with smoke. Then do something to goad him to fire at ghosts, like playing war-drums to feign a call to charge them. Get their arrows and your shields, stop the drumming, and then leave before the smoke clears.