Nyx Eclypso

"At an expense for the few whom you loved, you were ready to let hundreds, no, millions die. All for your selfish desire to protect a few people because you personally knew them. But, that wasn't true evil, so much as just necessity to keep them alive. So...pray tell, Amon, why were you willing to let a country, and its innocent civilians, die out of pure, pitiful vengeance?"

- Nyx berating Amon upon her "revival" Nyx Eclypso (ニックス エクリウプソ, Nikkusu Ekuriupuso) is the enchanted staff owned by Irene Belserion, enchanted using Shadow God Slayer Magic detached directly from Amon, believing it to be a "waste" when kept on him. Due to the soul of Nyx existing within the darkness, the resulting enchantment resulted in her "revival", returning her in a new body, after leeching off Irene's own power no less.

Nyx adopted the new title given to her by Irene, and accepted her return with open arms, enthusiastically naming herself the Jet-Black Magus (漆黒マギ, Shikkoku Magi), in addition to adopting new traits after spending some time effectively deceased. Due to her limited consciousness as a soul, Nyx's views and personality changed, for better or for worse, the prime change being her choice of becoming "Amon's enemy", displeased with what she witnessed and how he would usually turn out.

Trivia

 * The name "Eclypso" is an obvious reference to an Eclipse. This is to complete the theme of Irene's other two enchanted swords, Heine Lunasea and Juliet Sun, whose surnames are clearly based on "moon" and "sun", subtlely or otherwise.