She's in the correct here, don't bring modern sensibilities. They attack unprovoked, without so much as a warning or parley, and if they win a fair treatment is minuscule chance. Better dole out a taste of their medicine, and make absolutely clear she has greater strength (yes, subordinates do count) and ruthless will to use it than any adversary she's had.
I mean, I would do the same, especially if I have sansui.