Something I really wish for are constructible mechs as part of higher tier tomes.
If you think mechs and fantasy doesn't mix well you really should check out series like (especially) vision of escaflowne. Some game had medieval fantasy mechs like final fantasy (magitek armors in like ff6), White Knight Chronicles, Vanguard Bandits - and I think Super Robot Wars X had quite a few magic driven mechs as well.
OR perhaps as a new ruler type - ancient magitek armor only controllable by a select few. Uuuuuhhh this would be so nice.