It also, as the translation suggests, refers to units that make up the core of an army. Which leads me to believe that lore wise, kern is just a Battanian way of referring to enlisted men, like their tier 1 and 2 units. But in the case of the Kern unit tree, it might just be referencing the units in the tree as light infantry.
Then there is their cavalary, easily the best in the game. And their infantry too. All other factions have a best unit in a specific area, but the rest of their units are awful. Imperials meanwhile get something really powerful in every area. Palpatine guards are indeed the best way to take over the senate.Spearman is Heavy Spearman or Darkhan. Aserai Veteran infantry have a niche as a spearman with throwing option for excellent
Related: Mount And Blade II: Bannerlord - Best Units, Ranked. Army composition and how you use each unit can turn an outnumbered last stand into a striking victory. Using the terrain, breaking