What is its level compared to yours?
Did you research it? I haven't done that part yet, but generally when a monster near your level is very difficult to injure (especially on easy), it probably means there are specific oils, bombs, or signs that you need to use to weaken it. Generally those weaknesses can be found in books, notes, dialogue, or in the bestiary.
I am using IGN, cursed oil, and a potion that increases my attack... Don't know what else to do. It's level 8 and I'm level 8 too, so I'd think it would be a lot easier than this.
If you're talking about the part where [spoilers] the Bloody Baron tells you about Ciri and you get to play as her for a bit, I just smashed X (light attack) on the Werewolf and it died quite easily.
No... That was easy.