[Idea] Research & Development
I don't know if this idea can be implemented on Elemental : War of Magic, but i'm sure that it can be implemented to any Civilization type of game (or space 4x game).
My idea is to separate the Research & Development part in the research tree of the game. The Research Tree is more about to research the general Idea. It just like in Civilization game, where you can research automobile where you can get a tank, or flight that you can get fighter, etc. While the development is a new type of research that enhance the unit
For example when you have get a tank, you can enhance it's turret, from turret MK 1 to Turret MK2, or you can equip your tank with missile launcher, etc.
In Galciv game, it can enhance the research system. Rather than make it research Laser MK1 -> Laser MK2 -> etc, you can research laser, then move forward to research the other, but still you can develop your newly researched Laser technology to enhanced it.
In Elemental, the research section is the lost technology that you dig from... well, Lost Library or something. For example, you researcher finds that the ancient civilization has a unit name Knight from a scribe. The basic knight is about a unit with heavy armor, warhorse, lance, shield, and sword. it also noticed that a knight is a commander type unit can can command the others, has the ability to joust the enemy, etc.
Then, in development you can develop your knight to have better equipments, and more skills (passive and active skills). For example, you can give your knight the ability to shoot the enemy better (for example, give him the sharpshooting ability).