The blade oils provide quite a substantial advantage, especially once you can upgrade to the superior versions that do 50% additional damage. But you have to know which oil to use against each foe.
I can't find the Wild Hunt warriors in my bestiary, I've no idea which oil I should use against them and their leaders like Eredin. Which oil is effective against them?
Best Answer
The correct answer was found in the Official Prima Guide - it is Elementa Oil.
Edit: my old link to the forum no longer works. There is a picture from the book in another answer in this thread. I can confirm that it's authentic and correct.