Could this possibly be Neo? Definitely a female with some involvement with Torchwick.
The only thing that doesn't make sense to me is that she's later seen wielding a scimitar with a drastically different style from what we've seen Neo use. It might be nothing, it might be something. We haven't yet seen Neo fight under a post-Oum animation style, so it might just be a slightly drastic stylistic change if it is Neo.
I hold out hope that BEST GIRL IS BACK! GIVE US A REDEMPTION ARC WHERE BLAKE TEACHES HER HOW TO LEAVE A CRIMINAL LIFE BEHIND!
EDIT: It could possibly also be Cinder, as the style we briefly see as well as weapon of choice roughly lines up with Cinder's, but I think we'd all be a bit pissed if they killed her off only to immediately bring her back. RWBY may have somewhat lost the plot over the last season, but I don't think RT's gone full 343i yet.
EDIT 2: HERE SHE IS! SHE'S HERE! WOOOO!