Based on the Sankishin, the Sealed Weapon Izayoi and the Legacy Weapons, Nox Nyctores were originally created to combat the Black Beast during the Dark War. The first nine weapons were made during the war, but the tenth and eleventh weapons were made in the years following. The first Nox, the Gigant: Take-Mikazuchi, had its core split in two, one half fuelling the weapon, and the other half being split up and distributed to the other Nox's developed during the Dark War. The core of Take-Mikazuchi was made using the souls of those who died during the war. Valkenhayn R. Hellsing was offered a Nox to wield during the war, but he declined.
As they are a form of Ars Magus, they all require seithr to function, but only those exceptionally versed and skilled in the Art are capable of wielding Nox's. On top of those prerequisites, Nox's choose their wielders as all hold a certain degree of sentience when they possess their cores. This is what makes wielding a Nox Nyctores dangerous, as their sentience and self-awareness can greatly harm their wielder's mentality. This drawback happens as the Nox removes what it deems as unnecessary emotions, and places a greater importance on others, amplifying them; some eliminate all emotions when being used, while others heighten bloodlust.
According to Nine, the Nox's demand power, and that demand becomes mental pressure. The mental pressure then stresses the user, and through that stress the emotions and sensations of the wielder feedback to the Nox, making it stronger. If a wielder is able to control the pressure the Nox exerts on the wielder's mentality then the weapon grows even stronger as a result. Those swallowed by the pressure are unable to release the full power of the Nox, and it may even refuse to work for wielders without a strong mind.
After the Dark War, most of the Nox's had their cores removed by Nine, as the weapons had served their purpose. Deus Machina: Nirvana, Mucro Somnio: Musashi, Interfectum Malus: Ookami, Arma Reboare: Muchourin, and Phoenix: Rettenjo all had their cores removed, but the other Nox's went missing before Nine was able to find them. During the Ikaruga Civil War, Nox Nyctores were central parts of the war's mechanisms. Nirvana became entangled in multiple retrieval missions from both the Novus Orbis Librarium and Sector Seven, for example. In the years after the war, the NOL took interest in safeguarding the Nox's, having collected the Arma Reboare: Muchourin at some point. However, they did not actively remove Nox's from their owners as Jin Kisaragi and Carl Clover, an NOL major and vigilante, respectively, both held onto their weapons even though the NOL were aware of their presence.
Despite their drawbacks, there are a great many benefits to using Nox's. They are all remarkably powerful and each one possesses a unique ability. Unlike other weapons, they can also inflict scars on their victim's soul, something that transcends Phenomenon Intervention. Even with their cores removed, the Nox's still possessed abilities unlike any other weapon - Musashi is still capable of cutting through anything, even though it has not had its core for nearing a century.
Two versions of Lux Sanctus: Murakumo exist. One belonged to Nu-13, and one to Mu-12. The power of the Nox's has inspired similar weapons, specifically the Artificial Causality Phenomenon Weapons by Kokonoe and the Detonator line of weapons by Relius Clover. These weapons have similar powers and strengths to the Nox Nyctores, but aren't considered members of the category.
- Gigant: Take-Mikazuchi - destroyed. Previously owned by Seven and Eight, the NOL, Izanami. A version of it is currently owned by Juusan.
- Mucro Algesco: Yukianesa - active. Previously owned by Seven. Currently owned by Jin Kisaragi.
- Arcus Diabolus: Bolverk - active. Previously owned by Three, various other individuals. Currently owned by Noel Vermillion.
- Deus Machina: Nirvana - active. Previously owned by Celica A. Mercury. Currently owned by Carl Clover.
- Mucro Somnio: Musashi - active. Currently owned by Jubei.
- Interfectum Malus: Ookami - unknown. Previously owned by Hakumen.
- Arma Reboare: Muchourin - inoperable. Previously owned by Trinity Glassfille, the NOL. Currently owned by Platinum the Trinity.
- Geminus Anguium: Ouroboros - presumed lost in the Boundary. Owned by Yuuki Terumi, Kazuma Kval, Hazama.
- Phoenix: Rettenjo - attached to Kushinada's Lynchpin. Previously owned by Trinity, Tenjo Amanohokosaka, Bang Shishigami.
- Lux Sanctus: Murakumo - one was previously owned by Nu-13. One is owned by Noel Vermillion.
- Corpus Sepulcro: Requiem - destroyed. Previously owned by Nine.
BlazBlue: Central Fiction Library Entry
- Nox Nyctores Causality Weapon
Unlike Armagus, these take the form of Grimoires converted into weapons, smelted for fighting the 'Black Beast'. They are also called 'Phenomena Weapons.'
Smelting them requires extremely advanced techniques, and only ten were planned in total. Out of them, nine were completed by one of the Six Heroes, Nine, while the Dark War was still continuing, but the war ended before the tenth weapon, 'Murakumo' was completed. Several of the Nox Nyctores were lost during the war.
Utlizing them requires advanced Ars Magus, and not everyone can wield them properly. Also, there's a danger of causing massive strain on the user's mind. Creating the Nox Nyctores requires a large number of souls as well, in other words, humans. 
- Artificial Identity
An identity that smelts a Nox Nyctores within the Boundary. This forms the core allowing a Nox Nyctores to Observe itself, and further establish its own existence.
- Musashi is the only Nox Nyctores created during the Dark War that has ever been owned by a singular person - Jubei.
- BlazBlue: Phase Shift 3, Chapter 1
- BlazBlue: Variable Heart, Chapter 10
- BlazBlue: Phase Shift 4, Chapter 5 – Blue Snake's Crazed Play
- BlazBlue: Phase Shift 4, Chapter 3 – Demonic Human Weapon
- BlazBlue: Central Fiction, Library Mode, Weapon #011
- BlazBlue: Central Fiction, Library Mode, Powers #022