By far the safest and most foolproof method is to simply run in circles and Igni her to death. If you are a mage this goes pretty fast (you can get 41 dmg Ignis at lvl 7), but since there is very little speciaization at the level you can achieve the same effect with a Petri's philtre, the +4 sign damage armor from mysterious merchant, and a sword with moon runes.
Or if that sounds like too much trouble for your nonmage, you can still just run in circles and kill her with Igni, but it will take a couple minutes! :D
I also found a lot of success using Aard. Aard, attack twice, repeat, when out of Vigor run around a bit and regen it.
Post edited July 11, 2011 by aimlessgun