You're saying 2 mages can do more than 1 warrior... I agree.
But what if you used 1 mage + 1 warrior? Mage casts Oath of Desecration on warrior, and then casts Mass Slow on a group of enemies.
Warrior walks into the group of enemies and Whirlwinds. They are all dead because Oath + Bully + Whirlwind = massive damage.
If you only have a 20% chance of hitting enemies then you're doing something very wrong. Your main attribute is too low, or they're debuffing you, or something.