The Noble Phantasm that BB granted to this Alter Ego.
This Noble Phantasm strikes with more accuracy and does more damage the deeper her love toward the target is. Even if it's utterly one-sided, she will never let her loved one escape.
The Servant this Noble Phantasm was made from is the valkyrie, Brynhild, who appears in "The Völsunga Saga." The spear of love and hatred that she wielded in order to get revenge on her husband, Sigurd who betrayed her and wounded her honor. Strictly speaking, not the spear itself, but the deep love and hatred Brynhild felt for Sigurd that has taken the shape of a spear.
In "The Völsunga Saga," the fearless hero Sigurd (Siegfried) takes Brynhild, who was sleeping encircled by flame, as his wife. But afterwards, Sigurd betrays her, presenting her as his brother-in-law's wife. At first, Brynhild believed that this was due to Sigurd drinking alcohol which caused him to lose his memories and accepted these events as her immutable fate.
However, she came to know that, in reality, Sigurd had already regained his memories by that time. In the end, Brynhild killed the man she loved most in the entire world via a conspiracy and then freely took her own life in order to follow after him.