Has anyone tried taking a horse (for example, from Duncan), putting an elf with a sword on it (or a human with long ears and an elven sword), and attaching wings to the horse (even if they're from an angel)? You'd get a pretty decent Pegasus Rider. As for the current pegasi – they're winged unicorns, and that doesn't look good.
And if it were possible to create an ability that's the opposite of what mages do, so that it increases the cost of the enemy's spells, that would be amazing!
If you put in a little more effort, you could move the dragons far away (the light elves have boring dragons), lower the Ents to level seven, adjusting their stats and giving them a model of classic Ents (such mods already exist).
Lower the unicorns to level six, adjusting their stats.
Put the newly created pegasi on level five. Flyer, Magic Cost Increase. It should look pretty good.