If we do have enough without the Arete bonus from telling our Ninja to screw off, I do think it's worth it to bring her along then. As she said, she's not as good of a fighter as we are of course, but stealth is a novel capability that extends a lot of what we can do.
It's not the same as having it as part of Evening Sky, but alpha strikes of Fell Handed Stroke boosted by Cut Through and Ruinous Valor, fired off while we're basically invisible to an enemy for a vastly increased critical hit chance would seriously increase the range of beings that Hunger could challenge safely and reap great benefits from regardless.
Plus Gisena would be under the same protection! She could fire a blast of nullity that hits in tandem with Fell Handed to rip away any ablative defenses, allowing even greater damage to be done as the suddenly non-magical flesh has to cope with mind and soul bleed.