A non-playable character, she is a palette swap of Lenneth, using the same hairstyle. Her attacks are the same as Lenneth's, and is capable of using the Level 3 Nibelung Valesti attack even if the other 3 attacks miss. She fights exactly like Hrist does when encountered during the "A" ending, and has all of Hrist's voice samples, except her death samples, which are only attained during the "A" ending.
With a meaty 440,000 DME, she is a little more difficult to kill in the Seraphic Gate than her story battle, although if you've leveled a lot and/or have good equipment, she falls just as fast.She is worth seeking out to fight, because she is one of only 2 enemies in the game that drops a Glance Reviver sword in battle (Lezard is the other, but it is easier to knock a chest out of Dark Valkyrie, including the fact she respawns if you leave the room, whereas Lezard is a one-off battle). This is the same sword Lenneth has equipped in the battle against Loki during the "A" ending, and is highly recomended over any other sword, barring the Angel Slayer
Her death quote is actually 3 separate ones (like Lenneth's voiceover quotes in the "A" ending), that are pieced together one after the other.
"This is impossible! You creatures are but slaves of the gods! Ahhhhhhhughhhhhh!" - Dark Valkyrie's death quote.
The reason she is not referred to as Hrist in the Seraphic Gate is there are actually 2 enemy entries for Hrist. One is the story battle (which is a lot easier to kill), and the other one being this encounter.