Von Olitz in "God of Heaven: Save 2" is a relatively unique villain in the game. You will defeat him during the mission. You can choose to kill him or not. There are two options that are very big. The difference, first of all, is that if you let him live, Henry can avoid being seen as someone he has been trying to stop.
What is the difference between killing von Olitz in the Kingdom of Heaven?
Just like your decision on Brabant's life, whether to kill von Olitz will only affect one final scene in the game.
If you let him live, Henry can avoid being seen as someone he has been trying to stop. But again, von Olitz has always been the scourge of Bohemia, and perhaps he deserves the result.
Since von Olitz is slowly dying, maybe this choice will be easier for you.
You talked to him about the status quo of Bohemia and he tried to convince you that what Sigismund did wasn't as bad as you thought. Then, you have three choices:
Give von Olitz a decent death.
Kill von Olitz like a dog.
Let von Olitz survive.
The choice is on you.