I know, need practice to win.. They kill even me sometimes.. Anyway, like I said, more depends on your style of play.. I advise you to try to achieve even 2 points in Catalysis (the choice of potions to use in battle depends on your style) and to use always Quen, because it can save you from a killing blow (even now that it was nerfed..)
edit: anyway, maybe someone has better tactics.. I play Arena only few times, and I achieve max 110000 points..
for example, I never tryed in that fight, but maybe even Heliotrope can work well