Board Thread:Speculation House/@comment-35086897-20180411165727/@comment-26397825-20180415020844

The effect that was on Amber wasn't the small sparking effect to show they took a lot of damage but the full body breaking effect that both Mercury and Pyrrha had to show that the aura dropped to 0 - they had no aura left. That's why Cinder was able to shoot her in the back and have the arrow stick - there was no aura to protect her, so she literally got shot in the back. If she had aura, the arrow wouldn't have stayed; it would have hurt her but wouldn't have pierced her skin.