I think that one of the purchasable perks for the bow should be changing the arrow direction, e.g from horizontal to vertical. (Yes, I am are that this is a current feature, but I do believe it is merely cosmetic.) Another perk in the shop could be changing the arrow direction - not much, but enough to dodge enemies blocking. Although controlling an arrow may seem way too good to be true, it leaves you very open to attacks, as you are focusing on the arrow, not on yourself. To be clear, you will still be controlling your robot whilst controlling the arrow, but unless you are a master at controlling multiple things at one time, then you won't be giving much attention to what is going on around you.
Also, quick tip. I've been stupid enough to try to kill an enemy in front of an archer about to shoot. The archer's arrow passes through the enemy, killing the enemy - but also destroying me in the process.