I encountered the boss in sewer and it appears her attack range is wider than the red area marked on ground. In fact I didn't see any swing on her at all. It's 3 times already - she seemed to be doing exactly nothing but moving toward me, while I stayed outside of the red area by 1 meter or so, but still took heavy damage and died.
On the recap screen there is no mention of "Steel Cyclone", only "Grynkx, The Edge Who Hungers", though Steel Cyclone is shown in combat metrics.