Nei Sword drawbacks?

[Zucca]

I copied this from my another topic (because it was a bit OT there).

Is it just random when Neisword flashes off the corruptions from party members?
I rescently played PSII trough and got game over few times on that fight because everyone of my team was trying to run away and I couldn't do anyting.
And also I noticed that Neisword seems to cancel some good effects too:
When using Color Scraf to get party faster than Dark Force is quite hard to archieve. Even how often I used them Dark Force seemed to be faster sometimes. On Mother Brain that worked just fine.

[Mono]

I know that it cancels the corruption randomly. I don´t know about any collateral effects (maybe also canceling any status spell cast on that character?)

[Zucca]

That could be the reason why Dark Force has always been way harder to beat than Mother Brain. I need to do some investigation sometime...