Personally I find her double block is part of the appeal, and she does after all have the defense score to back it, maxing out at 599, which is decent even compared to heavies who are trying to block 4 enemies after awakening. That's also not factoring in that her defense increases as she loses health. Then there is her higher damage to kill blocked enemies faster, and the fact that her skill reduces all enemy attacks by 30% for 15 seconds which has a 1 second initial timer as a black unit, allowing it to be used in a pinch when the damage is looking to be too much.