In Ezekiel 17:7, this signifies an abundance of external knowledges of good and truth. (Apocalypse Explained 281[2])

In Psalm 68:13, this signifies the truths of faith from spiritual good. (Arcana Coelestia 8764, Apocalypse Explained 283[4])

Feathers broadly signify spiritual good from which truth is derived.

(Odkazy: Apocalypse Explained 283)