WarKirby
Arty person
Haste on a warrior isn't very appropriate. Dancing Blades would seem better, and Haste on Scouts.
So for a scout, you'd have a <PromotionAllow>PROMOTION_BODY1</PromotionAllow>, which means that if you ever get access to Body magic, all of your scouts can promote to Body 1 at their next level up and cast Haste. Warriors would get <PromotionAllow>PROMOTION_CHAOS1</PromotionAllow>, meaning if you get Chaos Mana they can pay a level to gain Dance of Blades for themselves. I would say you ought to link all magic spells to UnitCombat Adept and set things up so that every other unitcombat requires a PromotionAllow flag to get them so that you can expand this beyond rank 1 spells.
This system would let you set up a couple of appropriate spells available to units from the start of the game, or while Govannon is dead. Govannon is able to grant them the spells for free, AND can grant them ones normally not available (like Haste to your warrior).
I really like this idea, though I'm having trouble thinking of how to implement it
A UU for every amurite unit seems like the most feasible, if not the cleanest method. Auto aquire promotions could also be used, although they'd kind of clutter up the interface
Thoughts on what they ought to be...
Scout: Haste
Hunter: Floating Eye
Ranger: Treetop Defence
Beastmaster: Poisoned Blade
Assasin: Shadowwalk
Warrior: Courage
Swordsman: Enchanted Blade
Champion: Stoneskin
Phalanx/Immortal: Valor
Archer: Dance of Blades
Firebow: Force II
Can't think of much for the higher tier units though, or the mounted line.