Honestly, given the shit that Takamichi has put up with in the past and will in the future? Assault with a knife seems like something only a horribly scary psychopath would do to one of us because someone who has a knife when we don't is in a position of power over us.
Takamichi was probably barely even playing with her in that little 'fight.' The encounter lasted what, five seconds from start to finish? He was probably still thinking "Hahaha, did this bitch just come at me with a plastic knife? Oh god, is she stabbing me with a spork? This is hilarious. Still, I wonder what's got her so riled up? Is she from Mundus Magicus, fresh out of a war or what?"
After brushing off the attack like a kitten had just tried to gum him to death, him and the Dean confronted her about why she's so desperate to escape without even verifying if they're the good guys. They're in a position of basically absolute power over her and she's in a shitty enough headspace that she goes along with it and tells them the gist of what made her so crazy. From their perspective she's a great hero who sacrificed everything to save the world from an unspeakable evil, and paid a terrible price for it.
Mahora has a strange tendency to attract broken people like that anyway, so although her case is fairly extreme, it's not really unusual for them to want to help her out even if she doesn't have much power now. They give her a magical prosthetic, tell her to chill out because they can largely keep her safe while she's here, and then offer her a job because all the charity she's being offered makes her suspicious as hell.
Later things like Takamichi sharing his knowledge of the potential 'threats' in the class then make perfect sense. She's not Negi, she's not there to be tested and grow into a powerful Magi who can face her own problems. No, she's a proven badass who just wants the rundown of what to watch out for, so Takamichi tells her.
Eva gets curious later about what sort of seemingly completely powerless human can stare her in the eyes without flinching away feeling like prey, so in an unusually boastful mood she tries to convince Taylor that she should be afraid. She rattles off a ridiculous list of her accomplishments in the most showy way possible, expecting that Taylor will either not believe her and be set up for a 'horrified realization upon seeing proof' scene next full moon, or that Taylor will believe her and be afraid. Instead, Taylor is pragmatic enough to flip it around and rattle off her list of ridiculous accomplishments in the same manner to distract Evangeline and let her get in a cheap shot. Taylor's not over her experiences, but she's certainly pretty disconnected from them given the buffer that was Khepri, and this is a chance to start over in a different place.
I don't think anyone is acting horribly out of character beyond the reasonable amount of 'mental trauma softening' implied by the fact that she's now in a Comedy setting. Maybe there's something in the water at Mahora, who knows, but the setting is rife with people who have terrible backstories that should leave them in an asylum but they're funny happy people who can at least put on a facade of being well-adjusted when you don't look too closely.