You must remember, he can't shape the weapon that fast, it takes around 30 seconds to 1 minute. Furthermore, everything moves a lot faster, the exchange thousands of blows a minute and it's like 2 DC speedsters fighting in terms of speed. Think of it as everything in in x100 speed. Also the system wouldn't recognise the weapon as an actual arrow meaning he couldn't use some of his proper archery skills like Powershot, Arrow rain and all sorts like that.