Frodo is right. In the unupped meta, this obsoletes Tit. Shield since the ability is optional and therefore only used to your advantage.
As for my suggestion, it is mostly for thematic reasons and because it would be more mechanically interesting. Like you say, it would make little ingame difference. Similarly though, I would like to suggest that a flying shield replace any other shield when returned, rather than dying itself. Hypothetically, this could then be an interesting 4 element combo where you delay the flying shield until your Dim. Shield is about to wear off so as never to be unprotected. By no means a good combo but a cool use still.
What happens if the creature's stats are changed? Does that affect the shield in any way? Also, does it take 2 less damage from wardens and when gravity pulled?