I personally disagree with the idea that Istvan died too soon in KCD2. Heres my thoughts!
Henry needed a driving factor for KCD1, a sword that represents his connection with his father and a man that he can reach who keeps him from mourning that loss. Markvart would be that man, but hes too high up, too vague. Istvan is here, causing problems and hurting Henry in ways he can understand.
By the time you get to the end of tbe Trosky region secion in KCD2, Henry is already showing signs of growing past this need for an archor like Istvan. And by the time he is in Kuttenburg region, he doesn't need the sword and his fathers memory to push him forward anymore. The significance of rescuing Hans, meeting Sam and forming a found family with the Devils Den can not be understated in Henry's growth past Istvan as a symbol of all things wrong that needs to be solved.
You see how that growth is still painful for him, in that Istvan still haunts his mind. Him and Martin are turning from anchors to omens, ways for Henry to process the more complicated world of politics and war he now finds himself. Where people like Markvart, Erik and Sigismund are more complicated, and even his companions, like Dry Devil, are challenging.
Istvan was exactly the kind of antagonist Henry needed that first spring after the burning of Skalitz. By the summer, the world Henry has walked into is bigger than Istvan, and he has people like Sam and Hansand Radzig who help him grieve.
The one that Istvan died too soon for, was Erik. He was never ready to move on, he had nothing to hold onto when his anchor disappeared. To me, that makes Istvans death more interesting; that the one he wanted to find a place in the sun ended up falling, but the one he saw as like himself was able to move into something greater.
