Just to clarify Sir_Tainly's comment...
You need to change your AI script. Go into Viconia's stat page and select "customize". From there you can review the different types of AI that are available and see which one she is set on currently. As Sir_Tainly recommended, change this to a defensive AI and she'll stay the heck out of the way.
Optionally, you may also just turn the entire party's AI off.
Hope that helps!
