Katarina didn't put her blade down just yet- Grell did say impostors are running around the ship in her not. What if this woman is one of them. Only after additional few seconds she lowered her hand but didn't return her weapon back in its sheaths.

"But I don't know whether should I trust you. I didn't hear about Grell recruiting new people. I won't attack you - now - unless it proves that you are a fake." She returns her blade to its place.

She gives woman a warning look:"Also, never question my loyalty again. You don't know what I do for it," it was both a threat and information that things won't go so smoothly if she's questioned on this matter.