Fun fact:
It's also "officially" transliterated as Blazblue
http://www.jp-musicet.com/en/animene...-seven-ao.html
Same story as LisAni though:
"The title of the song is created by combining the words "brave" and "blue," being named so after KOHSHI (vocals), who is responsible for the lyrics of the song, got inspirations from the anime currently being broadcasted."