That shield on her ultimate is too powerful and to be honest shouldn't even exist. It gives her the ability to duel champions like riven/fiora/camille and actually win because their full combos can't deal enough damage to kill her through the ultimate shield.
Just look how big the shield is... She has 1.9k base HP in this picture so the shield is about 1.5k damage minimum:
Bruisers/assassins full combos only deal about 2k damage, meaning this shield makes her practically unkillable 1 vs 1. She can duel any bruiser and win it's disgusting lol.
Just remove the shield altogther, then to compensate increase the area size which she can dash to with ult. This leaves her with the ability to still reposition safely with the ultimate but without giving her crazy 1 vs 1 potential