In Psalm 18:45, when it says that the sons of foreigners shall fade away, it signifies that the temptations of people who are in good will gradually recede, and there's the promise of a new church which will acknowledge and worship the Lord. (The Inner Meaning of the Prophets and Psalms 268)

In Isaiah 1:30; 64:6, fading signifies the destruction of knowledges in the natural man, and also the perishing of divine truth in the church. (Apocalypse Explained 503[7, 8] 504[26])

In Ezekiel 47:12, the "leaf shall not fade" signifies that there will be no loss of knowledges of what is true in the coming church. (Apocalypse Explained 109[4])