I wished Byleth talked and had some dialog.
After a flying or horse unit dismounts, it should not be allowed to remount till the battle ends.
Removing Chest & Gate Keys (to make Thief more needed), however there needs to be an alternate long path (or a Gate Key far away).
Add some missions that would really require a tank class, or make units adjacent to tanks unable to move and only able to attack the tank.
I would really like the return of marriage + child units (from FE:Awakening).
A new mechanic which lets you defend better based on how good your skill is of the attacker's weapon (e.g. I have improved my sword skill to B+, so I take less damage from opponents attacking me with swords; and I would take even less damage if I increased my skill to A).
