The Ideal that I have in my mind would draw from not that many FE sources, actually.
Some of them I can think of are:
- FE8's trainee system, but expanded, combined with FE10's third tier, for four tiers of classes.
- FE7's multiple pathline stories, but once again, expanded, and even capitalized on
- FE4's Blood bonuses, but toned down and generalized.
- FE2's duality.
- Skills in general, but more like FE8 in mannerism. Still don't approve of most of the skills out there.