Just curious, would it be possible to add some penalty for spamming? E.g. a penalty on accuracy for each arrow fired without resting in between? 
Maybe 5 arrown then u get increased penalty for each following arrow and then 15s rest before you get accuracy back? Might be kind of semi-realistic... 
Just an idea... 
(playing as both shielder and archer)
Btw wo shield you should have a hard time against a group of archers, no doubt about it.