We use a few rules to help people not to fall back:
1) a wizard earns 10xp for each level opponent's wizard was above him. In three way games we make an average, rounded down. (we justify this by the fact that a wizard can learn more fighting against a more skilled one).
2) if at the end of the game a warband has collected half or less the number of treasures the other warband has (or the warband that has collected more in a 3-players game) we allow the player to roll one treasure more and discard the worst (we justify this assuming the warband has more carefully chosen the target treasures to go for, going for quality over quantity).
Also, we allow to sell grimoires with +4 and +6 spells even if the spell included is not known by the wizard.
And 5 turns limit, too, with a roll to eventually play the 6th.