The Seventh Seal and the Judge

The judge is supposed to be death and he's based on the character of death from the seventh seal. The instinct to war is the instinct for the truly free man that wins out over all others. Nietzsche denigrates quite a lot elsewhere in his book pity and mercy as weakness. It's actually not a moral good to take pity on someone, it makes you feel good in the moment but at the end of the day taking pity on someone and showing mercy is worse for everyone.