Suboxide
I think you need to look at it like the "Akilla Ash Storm"-title, it isn't in the 'the ...'-form and it tells enough about her.
Ash Storm is actually her last name, not her known by name, which is Cinder. So, if she showed her nickname she would be Akilia Ash Storm, the Cinder. I hope that clarifies how the nicknames work.
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JaliunSEM Arispotle