For those who wonder about it:
1- Dragon and Water affairs were obviously bad and mean.
2- As far as I can tell from the writing, I think the knight wasn't angry only because his son died, but because the full division died with him too; and, furthermore, "it was the last plan you devised". Maybe the sacrifice in itself was just pointless and victory would have been achieved through other means, i.e. negotiations.
3- The purpose of bringing the former tyrant back is to show the present king how he is deceiving himself. Of course, the tyrant was bad and nobody worried about his death, but the present king was doing bad decisions, SO NOBODY NOTICED ANY DIFFERENCES BETWEEN THEM.
Yeah, no actions profit everybody, but there are degrees.