I understand that shields cause clipping issues with back equipment and there is a way to hide sheathed weapons. This is not that. The breath effect is fine from the side - some part of the breath is not clipped by the shield. The issue is the transparency of Eidolon negates the breath effect of Wyrm's Breath Cape behind it. Of course "ANY" shield will do that, most shields are not transparent. I suspect Wall of the Mists has the same issue, but I don't have one to test. I'll check the wardrobe preview.