an upgade for a individual unit

[FiredClay]

I would like three techs
Metallurgy
Weaponcraft
Armorcraft

Metallurgy is needed to give the crafts more options at a price
Both weaponcraft and armorcraft would affect this individual unit like the church is affect when cathedral is researched. The other churches are not affected.
The crafts simply affect what is already there, making a good unit great but not invincible.
Once one craft is applied, the other craft cannot be applied to that unit

Metallurgy could give different and better options options at the price of more turns for better upgrades.

[COOLguy]

I think this is a pretty good idea. It would add some interesting things to the game.