Just had this thought and it sounded too badass to not at least try !
A passive ability for either the Orc or Dark Legion current/future units, SOMEONE needs this ability, someone EVIL.
Your units savagery and strength in combat lets them block incoming arrows arrows by using an enemy as a shield.
Increases chance of friendly fire, decreases chance of being hit with arrows. This is uniquely a defensive AND offensive passive, and its not just that it 'only works if archers are shooting you', since it also means archers might be better off NOT shooting that unit if its engaged in combat. I know a lot of people dont do that anyways because of friendly fire but skilled archers seem pretty good about that.