There are 3 mainline units which have two imperial age upgrades, Knight line, Militia line, and Mangonel line. Two of those are completely game changing. Paladins are significantly better against archers, and Siege onagers are the strongest siege weapon in the game. Champion, on the other hand, is a required upgrade if you want to even use them. Why?
This entire upgrade is sort of redundant, in my opinion. It inhibits infantry play, and champions aren’t that strong even against hussars.
So, here’s what I propose, make the upgrade significantly more expensive. Say, 1000 food, 800 gold. Increase the time required for the upgrade as well. Then, make the unit stronger as follows:
Champion:
HP: 80
Melee attack: 13
Armour: 2/1
Rate of fire: 1.9
Speed: 1.0
Attack Bonus: +5 to buildings, +8 to eagles, +2 to scout-line
Afterwards, restrict the unit to mainly infantry and archer civs.
Now, you need to buff the two-handed swordsman to a more usable level. So, here it is:
Two-handed swordsman:
HP: 70
Melee attack: 12
Armour: 1/1
Rate of fire: 2
Speed: 0.9
Attack Bonus: +4 to buildings, +8 to eagles, +2 to scout-line
To make a comparison, Cavalier upgrade is sufficient, paladin is just an extra. However, Champion upgrade is a requirement, two-handed swords are a weak unit.
Before anyone starts saying “BuT ThEY WiLL HavE No CoUnTER”, let me point out 2 things. First, archers will still work as a counter, so will cav archers. Every civ without good archers/cav archers have hand cannoneers. Of course, you also have units like the scorpions, and unique units like organs guns and cataphracts which can do the job.
“BuT No TRaSH couNTER”. Note that this upgrade costs 800 gold. That is a huge investment from your opponent, and you should have similar amount of resources as well. Buy yourself 20 HCs and you should be fine.
But also, that’s kind of the point. This is an end-game move, expensive and difficult to get to, and your enemies are going to have a hard time dealing with it. Same with paladins, same with siege onagers.
I accept that militia line is going to be garbage in castle age. Fine, it is what it is. But then, make it useful where it is supposed to be. i.e, late imperial age.
Let’s talk about trash counters for a minute.
All trash units are countered by other trash units. Halbs by skirms, Skirms by hussars, and hussars by halbs. This will work with just basic upgrades.
So, why on earth would you waste your precious gold countering trash units of all things? You need it for trebs and bombards to begin with. Let’s be clear, the idea was nonsensical to begin with. If you have a gold advantage, you’ve won anyway. And, you are better off spending that gold to upgrade something else instead of upgrading the militia line. This concept itself is a bit silly. We have no need of trash-counters.
EDIT:
The change to two handed swordsmen was added as an edit to better clarify the post