With my current Char and his 50 A-Star Swadian Army, I ran into Rhodoks yesterday. We even outnumbered them with another Allies Lord, 80 to 60 or such.
Half of my best men died in that battle, including a lot of dead Knights and Sharpshooters. And that was versus an outnumbered, unorganized, tactically idiotic placed AI Rhodok Army, while I tried my best to use Cavalry, Archers and Infantry to their strenghts.
I think it's their Spearmen and the large Board shields. Definitly not a pushover - I've been pounding similar sized Nord Armies in the ground with no problem at all, they simple fall in a rain of crossbow bolts while my Cav is running them over at full tilt. Didn't work with Rhodoks.