That's because she's fucking Trudy or one of your companions iircI know how to defeat D Knight but, I was thinking if anyone knows what is this exclamation mark? Is just for some free hits? And how to trigger it?
Edit: Some companions act as support in combat like Kirila healing you or Trudy getting fucked to distract the enemy,not completly sure how it works but I'm pretty sure that's what's happening.