A year and a half after she burned her blue "California Gurls" wig in a teaser video for "Roar," Katy Perry finally came through with her anti-costume promises for the Prism era at the 57th Annual Grammy Awards.

Not that there's anything wrong with costume Katy -- I loved her OTT Super Bowl halftime performance as much as the next pop fan -- but the change of pace was much appreciated.

Clad in a floor-length white gown and an equally floor-length, equally white cape (not unlike Solange's wedding dress), Katy performed "By The Grace Of God" as a trio of shadows danced behind her.

The understated performance was made all the more powerful by the introduction it received. In a pre-recorded video, President Barack Obama called on all artists present to take a stand against violence against women and girls, and he encouraged them to point their fans toward ItsOnUs.org.

POTUS was followed by Brooke Axtell, an Austin-based activist for survivors of domestic violence and a survivor of domestic violence herself. "Authentic love does not devalue another human being," she told the Staples Center audience and viewers at home. "Authentic love does not silence, shame or abuse."

It was a powerful performance, to say the least. Perhaps Katy should burn that blue wig more often.