Here "arm" represents Yahweh's power. Yahweh showing all the people of the nations that he is holy and powerful is spoken of as if Yahweh were a warrior who removed his cloak, baring his arms for battle. Alternate translation: "showed his holiness and mighty power" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])