[Taqwus]

Massed archers would have trouble with flyers and with heavily armored, fast units.

The former could actually -mostly- be countered with storms; sure, you sacrifice half your missile firepower, but it'll give you much more time to shoot the flyer before he reaches you. This will not, of course, hamper air spirits... forget about trying to ground Thuella, Queen of Elemental Air, armed as an SC (and who probably cast Storm and Wrathful Skies just before launching herself at your army).

The latter presents a problem. Crossbows will help penetrate heavy armor, but can still have problems and will get off very few volleys before that mass of Demon Knights smashes into you. Vans will be a big problem; while not heavy armored, they could be (think Marble Warriors, for instance), they're very fast, they have mirror images innately, and it would be very Vannish to have a mage ready to cast Arrow Fend to grant all his troops Air Shield-80.