Just to throw a new nasty idea into the mix, as I’ve not seen it elsewhere…
Given that she’s not entirely dead yet, do the Legion have a very significant incentive to unearth and deal with Oysingra before the Cinder King’s forces reach her?
Yes, he’s offstage at the moment… but if she’s still alive, presumably he could Break her if she’s captured?
Worst case, an undead Oysingra would be brought back to full power, comparable to Render and Zora.
Even without that sort of boost, she’d be a formidable threat (Lieutenant level), wouldn’t she?