The developers of this game seemed to have put a secret key into it for defeating the Khuzait, and that key is the Aserai. Guide to Aserai Troops (skip to 20:27 for Mameluke Heavy Cavalry) Mameluke Heavy Cavalry (Best for stomping on Khuzaits) They have two quivers of arrows, furthering their ability to do well in a siege.They're better than Arboreals, more plentiful and therefore easier to stock your castles with and forget about.They really have the same stats as most other tier five archers, except they fall a little short in equipment and armor when compared.They are equipped with a long sabre and recurve bow.They will still do a great job in a walled environment, but there isn't much reason to choose them over the other eight archers on this list. These guys are good for siege defense because if you're acquiring Khuzait units, it's for their horse archers and not these guys. The Marksman is perfectly average compared to its other tier 5 counterparts, and that just means it's twice as strong as it should be.
Khuzait, Khuzait, Khuzait… why would you EVER have a non-noble foot archer unit that was worth being in this list while the Battanians don't? I don't know, but they do.
Guide to Khuzait Troops (skip to 22:16 for Khuzait Marksman)