Thanks for the detailed reply. I figured it had something to do with the particular level 3's, but all my experiments yielded a game over when i hit the lvl3 mark.
The level 1 hero ach wil be easier than you'd think. Part of what makes the mage so strong is that you need only 1 stat and line of perks to be effective. The warrior needs next to 5 times the perks and 20 times the skill points to be as effective (i only ever leveled fade away). The fact that all classes have the same amount of hp is another point for the mage.
And yes, he can wear full plate. The only thing mages cant beat reliably is the fire elemental because its immune to the fire spells and even if pacified or paralyzed it keeps gaining lust which after turn 5 or 6 is an autoloss. Nothing else comes close.