Right, so the twist is that she's a killing machine with a sword. She might even be stronger than her master. She's very likely a former warrior who somehow got herself enslaved. Now the questions are how (with that skill?) and why.
I'm okay with this kind of twist, it's not bad actually. I mean, coming from Hamita it could be worse, the twist could be that he gets bored again and abandons this web comic for yet another new web comic...