I dont think the cooldown will have an effect. If I move armies one by one i can move unlimited numbers of bladestorms over each other. I approach your knights, make em instadie, retreat 25 sec. rinse and repeat. I think those ae damage abilities on units with a squadsize have to be removed until units actually block each other. Or it will always be exploitable really hard.
Same thing the other way around happens, if the guy spreads his army too late and like 10 squads are inside 1 tiny line and someone bladestorms close to them. Too much uncontrollable damage with that AE stuff as it is.