Blue Grimoire

The Blue/Pale Blue Grimoire (蒼の魔道書), also known as the BlazBlue is the so-called “strongest” grimoire, the “original book”, and can tap into the power of the Blue.

It was originally created by Yūki Terumi when he managed to receive a sample of the Blue during his lifetime, based on the original Book of the Blue Blaze.

Information
Despite being called a grimoire, its form is not that of a book, but rather a high-density mass of concentrated magic element similar to the Black Beast. Its original purpose is to utilize the power of the Boundary similarly to a Kiln, and it was smelted with the power to oppose the Amaterasu Unit.

It has no fixed form. In case of Ragna, it originally had the form of a jet black rock shaped in the fashion of a human without a head when it was in the possession of Rachel Alucard (which was Ragna's original body from a prior time loop that formed a Black Beast). After a younger Ragna touched it, it crumbled, turned into a mist, swallowed him in darkness, and then took the form of his right arm, despite still having the same obsidian blackness.

Ragna’s BlazBlue is remains of the Black Beast (which as aforementioned was his own body via a time paradox/time loop) which was deemed as a prototype and is also later on fused with the Idea Engine, which can allow him to access the true Blue. During the Continuum Shift, one of the probabilistic events was him losing the control over the grimoire, which absorbed him and turned into the Black Beast, who destroyed almost all of the planet.

One of the grimoire’s weaknesses is that it will remember the wounds that were dealt to the soul, to the point of transcending even Event Interference. Continuous corrosion of it, might even cause ruptures of other phenomena as well.

Another weakness is that due to functioning just like a Kiln, anything that can nullify magic element (such as Celica Ayatsuki Mercury's natural ability or Kushinada’s Lynchpin) causes the grimoire to cease its functions. However, the aforementioned Idea Engine with its abilities when activated in tandem can bypass these issues by acting as what Kokonoe dubs as a "noise canceller" via use of the true Blue. In Ragna's case, his right arm and right eye become crippled until he is able to use the Idea Engine's effects to be able to move both of them normally.

According to Litchi’s realization, the Blue Grimoire is like the Boundary itself, the Blue surrounded by limitless amounts of magic element.

Activation
Ragna used two different activation codes during the series:

Trivia

 * Ragna’s Blue Grimoire is written with the kanji 蒼, which means “blue” and “pale”, while Hazama’s is written with 碧, which means both “blue” and “green”.
 * Contrary to popular belief, Nu’s eyepatch is not a Blue Grimoire, but a magic power regulator.