In BKB it's really hard if you don't have generals with high command, because of titles and offices which grant stars. I played XL looong time ago and I don't know whether it was the same, but in BKB is strong emphasis on generals' stars, eg title 'Champion of the Joust' +3 command, +3 dread, also almost every other title/office gives at least 1 star, almost every province in west Europe gives +2 command, add heroes and high density of factions on the map to this and I see stars everywhere :P My salvation were spies, assassins, bribes, but above all - Grand Inquisitors. It would be much harder without unconventional methods of ridding of generals.

Generally I think that it's an exaggeration in BKB with stars, I remember that in vanilla Byzantium was really tough to fight, because of its princes with 5 and more stars. And it should be like this imho.

My kings' duel took place in fort's siege, so for my troops it was fight to the death, but maybe some enemy units were routed. Anyway it was epic, I wonder whether similar rulers' duels took place in history.