Ignis makes the most undignified sound--which he will never admit to later--when Gladio changes tactics, doing his best to curl into the man's chest so he can protect his face and neck from the assault. It will also, hopefully anyway, keep them from toppling over should Gladio continue despite it all.

"Blast it, Gladiolus, stop! I will be most cross with you if you reopen your wound after all this!"

Thank you very much, he's had enough of your blood on his hands to last him a lifetime at this point.