In Psalm 58:3, a womb signifies that good is to appear, and the belly, that truth is. (Apocalypse Explained 710[5])

10600. Finally the subject is the internal and Divine substance of the Word, the Church, and worship that shines through the external form these take, though not before the eyes of that nation. This is meant by the gleaming of the skin on Moses' face, and the placing of a veil over it whenever he talked to the people. These matters are dealt with in verses 29-end.