When BB used her abilities to create the Sakura Labyrinth, Saber and her master, Kishinami Hakuno were brought to the Far Side of the Moon Cell along with many others Master and Servants from the Moon Cell Holy Grail War on the Near Side. Saber Bride is the alternate costume for Red Saber who appears in Fate/Extra. Her true identity is later revealed to be Nero Claudius Caesar Augustus Germanicus, the Fifth Roman Emperor.
A stunning cosplay by Selena Adorian with photography by Salvarion! It looks like the ends of her skirt are really burned off, then same with the game version! Please check out her Deviant Art Gallery for more of her photos! Thanks to Grace for sending this in!
Source: Selena Adorian on Deviant Art