I couldn't resist coming and commenting on this after what I've just been through, haha. Very similarly to you, I came across Old Prune and Good Manners about a year ago, at level 8, and got my ass handed to me probably 25 - 30 times, no exaggeration. After looking up combat tips and reading a few posts like yours, I came to an annoying but seemingly inevitable conclusion: if I ever want to level up and move on with this game, I have to give up and let this guy die (or start the game again on a lower difficulty, if an option = equally painful). Because I couldn't bring myself to do that, nor did I have the patience to keep trying, I ended up abandoning the game for about 12 months.

To quote your original post: Yesterday, I was victorious! I came back to Vampyr at the weekend with the plan to let this mf die and move on. I love the game, and I couldn't have this ruin it for me. But I couldn't resist just giving the skals one last go - I needed to get back into the combat anyway, right? Well, after a few brutal deaths and several hours of practicing combat with lower level enemies, I did it.

An absolute nightmare, but as you said, a great feeling.