Lucy was still in her eagle form when the fight between Sera and Azriel happened, she tried everything but her body didn't move. Every couple of second she made a wing beat to stay in the air, but that was all.
In the magnificent light of Sera's power, she got her mind free from the lethargy of death, and even managed to move her body a bit. Slowly her control increased more, but just as she was about to go and help, a scream even louder than the constant thunder broke the skies.
Her heart cracked from the sight of a shining figure falling towards the ground, her right wing cut in two and bleeding...
Lucy never saw Sera's wing bleed, it only got bloody for a second or two before repairing and cleaning itself. Now the whole thing was red and the droplets of blood fell towards the ground, like the rain from the clouds above her head.
The angel of death didn't even wait for her to hit the ground and started his descent immediately.