player.additem 1397F 5000
inTyping player.additem 1397F 5000
into the console will give you 5000 steel arrows, then you can give them to your follower.
I choose steel arrows for balance as to not be OP. Without the followers fletching for themselves I feel this is fair for archer followers, nothing more annoying than your archer running in with a cheap dagger.
Never saw Legolas run out of arrows?