Well, I want to point out that the Rhodokian sergeants become invincible murder machines, if you command them correctly.
I was able to mow down rows, upon rows of Swadian Knights when I used my secret technique. Swadian Knights... they who are seen as cheats.
Nords are quite a pain in the ass, if you use Rhodoks. Nords however are destroyed by Swadian Knights. I recommend to annex the Swadian territory first and then launching a full scale invasion (with Swadian Knights) on the Nords.
What my secret technique is, is pretty much practiced throughout history. Primarily by the Romans.
It's the Testudo (turtle) formation.
It's a shame you can't have shield placed on top, or else they literally would be invincible.
How to do it:
1. 'hold this position'
2. spam the 'stand closer' option with your infantry
3. destroy the enemy
This may seem simple, but it's really tough to break through twenty sergeants, each one of them equipped and skilled to the max.
Sharpshooters are a pain to the ass, too, if you aren't immediately rushing and charging. I have tried both, the sergeants had better results, but the sharpshooters were pretty ****ing cool too.