Power of authority v. authority of courage

Iliad 9.38-39. Diomedes to Agamemnon:

σκήπτρῳ μέν τοι δῶκε τετιμῆσθαι περὶ πάντων,
ἀλκὴν δ᾽ οὔ τοι δῶκεν, ὅ τε κράτος ἐστὶ μέγιστον.

Zeus gave you a scepter to be honored over all/ But didn’t give you courage, which is the greatest power.