I ...actually don't think I'd be surprised if Azami really did intend to kill Hinako in this moment.
The thing she wants to do most is hurt Shiori; she can't easily kill the mermaid, but if she's sussed out just how much Shiori and Hinako care about one another (and if she's been watching them this entire time, then I have to imagine she's aware to at least a fair extent), then killing Hinako would undoubtedly cause the most pain possible. Hinako is merely a means to an end for Azami; she held out some small hope that she could turn the girl against Shiori, though I bet even Azami saw it as a long shot (again, because she's been watching them all this time).
This was sort of a hail mary attempt, of sorts, then. Talk to Hinako, see if she can be persuaded, but without really betting on that being the case, and plan accordingly.
It feels rash of Azami at first blush, but at the same time I could see it being a culmination of factors in the plot to this point. I think the part that makes this feel...."off", is the circumstances of their setting. It feels incredibly intimate, being in Hinako's hallway of her home, ostensibly with none of her friends/allies nearby (that we currently know of).
But again, at the same time - it's the perfect time for a big escalation in tension, because of the classic horror trope of blindsiding the audience when it feels like the tension has drained from a scene/story beat. We've come off the back of Hinako the extent of her feelings for Shiori, and Shiori's feelings for Hinako, and that's with the revelation of Azami's part in both of their stories, and her intent toward both Hinako and Shiori. There was a lull and a depression of the plot's tension in the wake of the festival and with tender moments between Hinako and Shiori, and -- even more important for horror tropes -- this is now happening in the "safe space" of Hinako's home. The place where even Shiori and Miko thought it fine to send Hinako into on her own. That might be even more reason to believe actual intended violence is imminent.
I ...do not expect anything to actually happen, though all bets are off with this series. I have a few thoughts on what might transpire if Hinako is actually attacked by Azami and Shiori or Miko don't get there/get there in time, and what might transpire if Azami doesn't attack her here, or if Shiori does intervene if Azami does. But there's still too many unknowns at present with this cliffhanger to say for sure, so.
We have 2 chapters left of this volume, though, if we're keeping to the same sets of 6 that we've had up to this point. That leaves whatever's about to transpire between these two now that Azami's picked up the scissors again, with a potential intervention, and then the immediate aftermath of this scene and incident after the action itself concludes. I don't see the story ending here, as there's just too much still to cover (even if Azami's arc itself is somehow concluded, which I also don't see happening in two chapters' time in any way).
But we're in the thick of it now, for sure.
Thanks for the TL work as always.