of. Genitive of cause, the power being the cause of the pride. your great pride. Compare Ezekiel 30:6. So Ezekiel 24:21, where the sense is lost in Authorized Version by the rendering "the excellency of your strength".
Related Commentaries of Leviticus 26:19
Leviticus 26:19
19 And I will break the pride of your power; and I will make your heaven as iron, and your earth as brass: