Heart of Stone

True darkness was Sunny's natural enemy. 

However, to Saint, it was a weapon. 

Because she had been born in the Underworld, where darkness reigned. 

[Heart of Darkness] Attribute Description: "A vestige of an ancient darkness dwells in this Shadow's heart, granting her tenebrous powers."

[Mantle of Darkness] Ability Description: "Darkness embraces this Shadow. When surrounded by darkness, and true darkness more so, her swiftness and might will increase. Her wounds will be healed, and her heart will grow fuller."

[Blade of Darkness] Ability Description: "The true darkness dwelling in this Shadow's heart can be summoned in the form of a fearsome weapon, as long as the Shadow has mastered the use of that weapon. The Blade of Darkness can slay those of flesh and those of spirit; it never dulls, never falters, and never breaks. Alternatively, the darkness can be summoned to augment a mundane weapon."