BotBM

This stands for "Blade of the Battle Maiden". (Sidereals, p. 180)

Requires MA 3, Essence 2, and is the second Charm in the Violet Bier of Sorrows Style. Scene-long dice-adder. Is the source of much contention, re: "is it too powerful?"

~

I think its deeper down the tree than that. -MeiRen

No, it's not. Blade of the Battle Maiden is a 3/2 Celestial MA Charm with one prerequisite (Secrets of Future Strife).
~ Shataina

Sidereal charms in general don't really follow the idea that powerful charms need to be developed off of lower ones. -BogMod

...which might be seen as a design flaw, particularly when applied to a MA style that is arguably available to other Exalt types. -szilard

It's definitely available to other Exalt types. It's a normal Celestial style, and developers have explicitly stated that it works the same as all the rest in that regard.
~ Shataina

"Possible to learn" and "available" are two different things. VBoS is the special techniques of the most secretive secret society in Creation, so I'd imagine non-Sidereals would require extraordinary circumstances to gain access to it. Obviously, this is a fluff barrier rather than a crunch barrier, but it shouldn't be entirely discounted. -Ben-San

Given the existance of First Age memories and the ability of, at least, Solars to learn charms based off of them, even the fluff barrier isn't much of a barrier here. -Lurker with Run-on Sentences.