I disagree with you on that Raine.
Don't ignore the fact that she oneshotted an arrancar. Granted that it was a weaker one and not necessarily amazing but it shows she is definately high officer capability.
Being an Arrancar doesn't automatically make you a badass. Most of the Fraccon we've seen are either at or slightly above the level of your lowest-rung Shinigami mook. D-Roy was crap, we've always known that. Not only did he suck even as a Hollow, but Grimmjaw permanently cripplenerfshanked him by biting a honking huge chunk of his mask off when they first met. So he was an already weak Hollow made even weaker via events. And he wasn't even that hot of an Arrancar, seeing how the only reason he got to come along was because he begged (they flat-out told him he was too weak to be of any use). And he was stupid, which is something of a death-warrant in and of itself.
Plus, he never even got to release
or fight with his real power, at least according to him (he never released, and stated that he was an 'aerial' type that only fights best in the sky). He was about to, but Rukia oneshotted him with a Shikai move before he could finish speaking. And that is a move, I'd like to remind you, that
is flat-out stated to be lethal should it connect, though I won't press the subject, seeing how we had a monster argument about it a few months ago.
If anyone was going to get oneshotted by anything, it was D-Roy. Killing him is nothing to brag about. And he got killed by someone who not only isn't a moron who runs their mouth in life-or-death situations, but who also has a Fatality technique in their Shikai moveset.
D-Roy got completely and utterly boned from start to finish. He's not a very good example at all.
But she also defeated one of the Espada. Which if you go by their ranking should be more powerful than the fraccion of other Espada, which several of the Litenaunts had difficulties with.
Except that Aa
didn't go by ranking. He was the exception to the Espada rule, not only because he lacked the raw power, but also because he wasn't evolved enough (The Rule? is supposedly only Adjuchas can become Espada, and he was a Gillian).
They only made him an Espada because he had stupidly useful and insanely broken special powers out the ass. In terms of strength, he was by far the weakest of all of the Espada, bar none. Given his relative strength compared to Rukia's, and her strength compared to other known Shinigami, he was at
best the level of one of the higher level Fraccon (the badass ones, not the dime a dozen ones). He got the position not because of his power, but because of his
abilities. They were just that damn useful. Hell, the blanket telepathy alone was probably worth the promotion, to say nothing about the ability to eat Shinigami and Hollows and assimilate their powers.
Pardon me, but isn't it sort of Canon that Big Brother Byakuya is using his influence to keep Rukia out of an officer seat because he doesn't want her getting hurt in those "Captain and High-seat officers only" battles?
Yes. That's why she's ranked as a 13th Division mook, and not a 13th Division Seated Officer.
In the least, by being able to kill an Espada that should put her in the running for Litenaunt Capabilities, the low range of them but still Litenaunt.
I flat-out reject this. If they had meant Lieutenant, they would have
said Lieutenant. They didn't. They said "Seated Officer."
The most optimistic you can possibly be is to call her 3rd Seat material, and I would fight that tooth and nail. She's mid-range Officer material, not upper Officer material.