[@GrafRoy Zeppeli]
-How old was she when the family pronounced her a failure and just churned out another kid? That seems like the sort of drastic move you wouldn't do prematurely, especially since she's got good latent talent. 

-Also it's worth noting that families really only teach one kid the magecraft to begin with because of how the more people there are who know the magecraft, the weaker it gets. They'd be hesitant to teach two kids magecraft to begin with, let alone to keep teaching the one who isn't the heir anymore. That's why Sakura got pawned off to the Matous. 

-Keep in mind that healing grevious wounds and fatal injuries is a pretty big thing; if you're ever trying to heal someone from the verge of death, for instance, expect it to cost quite a lot of jewels.

The main snag is this thing with the family you're wanting to do. Something like her having a sibling she competed with to be the heir would be feasible, but if she lost then she just wouldn't be taught magecraft to begin with, and probably wouldn't even know it existed. 

I'd probably say the better way to handle this would be that, instead of saying she got disowned as the heir, say she got disowned as the family's representative for the Grail War. The Tohsakas care about it a lot, after all, and she'd probably have been told about it from a pretty young age. Doesn't want the responsibility, starts screwing up, family decides to hire in outside help, she gets mad, bam. That's probably the cleanest way to thematically do what you want while still making sense for the setting.

As an aside though, the phrase "Expert, knowledgeable and powerful mage" really has no business going anywhere near a Tohsaka at this point in history.
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[@Breo] Looks good. The 24 hour window will be up in case anyone gets a Rider sheet in before then, but otherwise you'll get the slot.
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[quote=@Ijoyen]
I might as well give it a shot. Will attempt a Master.
[/quote]

Alrighty, let me know if you have any questions!