Rather than Archers (particularly longbow yeomen) switching between flaming and normal arrows, would it not make more sense for them to switch between broadhead and bodkin arrows? Broadhead is more useful against cavalry and bodkin against armoured targets. If possible the button could make them switch between all three, although Im no modder so Im not sure if that would work. Or maybe flaming arrows would only be availible during a siege.

Let me know your thoughts.