Interesting. If her serious brutal personality was conceived at the time of her creation, then the fans are (perhaps) making it more complex huh?
I should stop theorizing about subjects with scarce information, but I am unfortunately cursed with curiosity. Some of the art of her on pixiv are extremely interesting to form theories of.
She's only brutal because her era lacks the spellcard rules, so unlike Reimu, she actually has to kill Yokai. Thus her suited for combat modified Miko uniform which Reimu adopted. And her general request that the Yokai she has to kill stop it so she won't have to,
(Also the rattles she's using are an item Miko use during one of their ceremonies. I think it's used in some ritualistic dance.)