I suspect this was all set up by the siblings - she can't learn martial arts? Then how did she become a vengeful blade that finally destroyed the blood cult at the beginning of this story?
They likely tried to make her seem unimportant so she wouldn't be a target, thus faking her 'blocked meridians' or whatever.
This would also explain why the rebellious brother is being quiet - he knows she feared this, and now they're the ones doing this to her.