Sealed Weapon Izayoi
Sealed Weapon Izayoi
Sword, shield, whip, clothing
The Sealed Weapon Izayoi (封印兵装・十六夜) is an Ars Armegis weapon that was created during the Age of Origin. They were produced to not combat the Black Beast, but Observers. It is the pupal form of the Zero-Type Izayoi, and the prototype of the Lux Sanctus: Murakumo. It is best described as a 'shield', compared to its evolved form's 'lance'.
Also known as the Murakumo Unit Prototype, the Sealed Weapon Izayoi is a unique weapon that serves as clothing for a wielder, as well as a shield and small sword. It is unique among weapons in that it was designed to combat Observers by stealing light on several electromagnetic wavelengths, including radio.  As well as this, it enhances the user's natural abilities by using light as a catalyst.  There is a large drawback to this, however, and that is that Izayoi steals light from its own wielder.  This means that by continuous use, it can make its wielder blind, and in the worse of cases, can kill them.  Despite this, it's implied it's possible to counteract this trade-off by having a strong will and mind.
Prior to the Dark War, one of the Sealed Weapon Izayoi's was kept within the Magister's City of Ishana. Hidden deep within the Cathedral, it was eventually rediscovered by Nine the Phantom after her ascension into the Ten Sages. It was entrusted to the Yayoi family by the Mage's Guild and given to Ayame Yayoi to wield. Its usage eventually killed her.
After the Dark War, the Yayoi household harbored one of the few Sealed Weapon Izayoi's deep underneath their family household in the 4th Hierarchical City of Naobi. The only way to access the weapon within the family vault is with a drop of Yayoi blood.  One of the most powerful abilities of the Izayoi is to deploy a Zanki Barrier, a high level Ars Magus that creates a space sealed away from the rest of the world.
In terms of appearance, Izayoi is a changing weapon. The clothing of Izayoi is simply a cap with a large eye on the center, and two small wings on the sides. The blade is similar to a gladius and looks very similar to the nib of a fountain pen. Izayoi's shield is in the style of a large tome which can open to unleash its own style of attacks; the spine of the book is also a large eye. The colour of Izayoi's clothing can also change, and has been seen in cream, black, and white.
The location of Tsubaki's Izayoi is currently unknown.
BlazBlue: Central Fiction Library Entry
- Sealed Weapon Izayoi
A sealed weapon possessed by Tsubaki, which served as a model for the Nox Nyctores. It's also called the 'Murakumo Unit Prototype'.
It raises the user's power by several times in exchange for their 'light.' The above ability is merely a 'side effect' however, as its true power is the complete absorption of a specific wavelength of light, serving as an 'Anti-Observer' weapon. It can even fully neutralize Phenomena Interventions.
Once awakened to its true power, it becomes the 'Zero-Type Izayoi', a 'lance' known as the 'Immortal Breaker'. 
Izayoi (十六夜) is short for izayoi no tsuki (十六夜の月), which is the first moon after the full moon, and the start of the waning moon.  The waning moon is when it begins to lose its brightness; this naming convention is likely in reference to the Sealed Weapon's ability to steal light.
- BlazBlue: Central Fiction, Library Mode, Weapon #018
- BlazBlue: Continnum Shift, Help Me, Professor Kokonoe! Iron Tager's segment
- BlazBlue: Continuum Shift, Story Mode, Iron Tager - Loyalty
- BlazBlue: Continuum Shift, Help Me, Professor Kokonoe!, Tsubaki Yayoi's segment
- BlazBlue: Continuum Shift, Story Mode, Tsubaki Yayoi - Regret Sin, Bad Ending
- BlazBlue: Central Fiction, Izayoi Arcade Mode, Act 3
- BlazBlue: Phase Shift 3, Chapter 1 - Battlefield with Blue Sky
- BlazBlue: Phase Shift 4, Chapter 2 - Sweeping Away Crimson Grief
- BlazBlue: Continuum Shift, Story Mode, Tsubaki Yayoi - Regret Sin
- BlazBlue: Central Fiction, Library Mode, Weapon #017