The European civilizations have an ambiguous mechanic for the requirements that the remaining non-European civilizations submit, They have certain very useful things that the Europeans do not usually have, for example (Invisibility, long-range siege from an infantry, Certain bonuses, auras, regeneration of life, formations, big button skills in unit)
The european armory is generic for all except the musketeers melee upgrade it doesn’t have it for civs that don’t have a musketeer-like unit, I think you could remove some generic upgrades and add some exclusive to certain civs, you could also generate a better balance, for example it would be wonderful if the Ottoman could investigate something that increases the damage multiplier of the howitzer against light cavalry, that the Spanish buff their melee units a bit,
In general, only 2 improvements are almost always used, the one of the goons that gives +2 range and 10% damage and the one that increases the multiplier x3 against the heavy infantry by parts of the skirmishers, at least in 1v1 it is so
That would also help to specialize a unit more, or perhaps give a slight support to an obsolete one, although I understand that civilizations should only have a strong set, so as not to make it difficult to counter, for example the halberdier in France, Russia and the Portuguese It practically doesn’t exist either.
An idea that I have is that the units that are real can be accessed to exclusive improvements of the armory for example
British: Musketeer - hussar
Spanish: Rodelero - pole vaulter - third piquero
Ottoman: Obus - tartaro
German: Ulano - skirmisher
Those who understand the concept of real unity, understand what I mean
I know that this will be complex to carry out and even bad ideas could lead to a disastrous balance, it would practically be a rework of the arsenal but hey, read them