UNIT - Creature Balance + Visual Changes

Agile riders indeed have damage that is ≈2-2.5 times lower than dark riders with a charge, even if you increase the random attack to 100%, this clearly won't be enough.

Here are a few ideas:
1) Balance them out with stats, give the alternate upgrade increased damage and slightly more survivability.
2) Give them the ability "Double Strike," but reduce the damage slightly.
3) Give them the ability "Swift Attack"; almost all heroes from the faction have the spell "Slow," so this ability would be useful...
4) The least radical option would be to give them the ability "Giant Killer," which would give them a small bonus when attacking large creatures.