There is a difference between a dark hero and a soldier that is neither "dark" nor a "moralfag"
In battle, soldiers kill people when they fight, and they intend to kill, you can't take prisoners all the time.
especially if they fight to the death.
You kill them so they wont come back and kill you nor your loved ones, that'a "true" MORAL, if any.
unless you can defend their behavior? their behavior isn't right, basicly, what they are doing is increasing the risk of bad guys who are going to maim his/her friends the chance they get, and in many cases, they do succed in doing so.
Thus, I would like any argument on why sparing your enemy if they already killed one of your friends ALREADY and is going to do it again and again whenever they can.