Cerydra or E2 Phainon?

Potential spoilers for Cerydra’s kit(?)

Hello! I hope everyone has been enjoying Phainon’s release and the new patch 😄!

I summoned for Phainon when the patch dropped last night, and managed to get him to E1S1 and lost the 50/50 when going for E2. Should I just wait to get his E2 on a rerun and use this guarantee for Cerydra? Particularly if she’s supposed to be a good support for him? I haven’t pulled for limited eidolons before this so im torn on what to do.

Thank you so much for your help and hope everyone has a good rest of their day!!!