Comparing Nina's slashes to Eris's, they weren't especially fast. On the contrary, they were just a tiny bit slower. When it came to the heaviness of their strikes, Eris's ability to overwhelm was probably higher.
However, Nina's strike was a strike that wasn't fuelled by her emotions. There was no bloodlust at all; without even preparing her emotions, a single strike. Let alone bloodlust, Isolte couldn't even sense any intent to strike.
"However, the results were satisfactory, weren't they? How about it? Do you want to learn Water God techniques from me?