Problem: the leader dehumanizes someone
The leader dehumanizes someone. The leader may underestimate either someone's agency (their ability to plan and carry out action; in Iliad One Agamemnon underestimates "old" Chryses' ability to exact revenge) or someone's experience (i.e., emotional complexity), either a rival or one of his/her followers.
WHY it's a problem
Dehumanization may cause the leader's authority to be challenged by a rival or may lead to the low morale and minimal effectiveness of the followers. For example, in Iliad One Agamemnon underestimates the agency of Chryses both as an old man and as a priest of Apollo (perhaps because Agamemnon trusts in his support from Zeus, the king of the gods; cf. Iliad 1.174-175). Doing so makes his army vulnerable to Apollo's plague, which Chryses summons to avenge Agamemnon's unwillingness to ransom Chryseis.
QUESTIONS to consider
What causes a leader to dehumanize others?
Can a leader choose not to dehumanize?
If so, how would you instruct a leader not to dehumanize others?
FURTHER READING
Nicolas Epley's Mindwise: Why We Misunderstand What Others Think, Believe, Feel, and Want.
Bain, Vaes, Leyens, edd. Humanness and Dehumanization.