I would completely rework Thunderers. As it stands, they don't compete with Irondrakes; it costs the same exact points to run 20 Drakes that it does to run 30 Thunderers, and running them at 20 means if you lose a single model their accuracy buff vanishes. Quarrelers have a similar issue, but at least they're better in melee and you get more OVERALL shots at a 30 man unit, so an arguement could be made.
I'd also like to see Warriors brought up to par and made slightly beefer. They have a 5+ save while donned in chailmail, which is the same save a bunch of half naked elves and snake ladies get, which makes no sense.
Lastly, make Unforged NOT terrible. Maybe buff his saves value or give him a ward save of some kind?
One other overall thing I'd like to see is a way for us to deal mortals a TAD more often.