I may be a little slow. The "previous" Weiss did all this cruel stuff... while 13 years old or younger? Because at this point, he's now barely 15, old enough to begin to enroll in the academy.
I'll be real, because of how the plot is kinda about MC trying to fix the previous owner of his body's mistakes, she is likely among the ones that deserve the most to get something back and be treated well after what "he" tried to do to her.
Also, are some of you guys not seeing that something's off about her proposal for a dance ? Something's about to happen next and its really obvious.