A 'stretched out arm,' as in Exodus 6:6, signifies omnipotence or divine power, because 'an arm,' when stretched out in the heavens, represents power from the divine, but when not stretched out, but bended, it represents power in the general sense. This is why divine power is often shown in the Word as a stretched out arm or a strong hand.

(References: Arcana Coelestia 7205)

In Isaiah 21:13, this signifies to be no longer in goods and thus desolate. (Arcana Coelestia 3240[4])

In Deuteronomy 19:5, this signifies to bring doctrines under discussion, for a forest signifies what is religious. (Arcana Coelestia 9011[4])