When I first started fighting ghouls in mod. 3.03 I developed my own tactic for fighting them. I call it whack and back. You deliver 3 or 4 blows in strong sword style, then back out fast to avoid the ghoul's blows. It seems to be pretty effective at killing them. After I stole the Igni sign from the crypt (and escaped with my life) it got much easier. When you develope Igni to the point that it is capable of causing fear, it's a really devastating weapon against undead. Any undead suffering from fear can be hacked by sword with immunity. While in fear they try to flee from you and do not fight. This has held true up to Bruxaes and Alps in chapter 4.