Thinking about militia line

Foot soldiers are quite weak and easily countered, with goths being the only civ to regular make infantry.

So my proposal to improve this is to simply give for each upgrade (M@A, Longsword,2handed sword, champion) an extra +1/+1 armour.

This way they are less countered by even unit in the game archers/trash/knights. However against things supposed to counter infantry (hand cannons, siege) due to the high base damage and the bonus damage they would still be effective.
Archers and knights still would be able to exploit infantry's slow move speed, but would struggle more in a head on engagements.

Also by making the armour scale with upgrades they would not suddenly be super powerful but would rather scale with the ages making them more valuable through out the game.

I really think that this is the simplest solution for improving the militia line without having to many unintended consequences.