Geralt de Rivia, though a warlock (witcher) in the books, isn't the kind of warlock you find in D&D.
He's a mutant, trained beyond human limits of speed, agility and balance to be near undefeatable with a sword and to grasp the basics of magic to give him an edge over the monsters he hunts and to warn him of danger. He definitely owes no allegiance to some demon or fey, he's made no dark pact with evil to achieve his power. He doesn't curse anyone and he doesn't blast off magic spells and fight at a distance.
I don't think warlock actually fits here. Avenger gets you closer, a lot closer. So does a swordmage.
I love these books actually. The quality of the writing and the mastey of the narrative goes far beyond what is usaully found in the fantasy genre. Actually, I think the story is a masterpiece. I'd quite like to play the video game. the demo on youtube looked pretty good. I'm actuall reading the last part of teh final book in the series right now ... actually I'm going to do that literally right nowI'll have a think and a play around with the idea another day and then come and post up a possible build.
Well, I wasn't literally trying to make a clone of the character; just using him to draw some inspiration from. As I said before, I have not read the books, and the second game is the entirety of my experience with the character.
Having taken a gander at the Hexblade, I think it works nicely for what I'm after - good mix of sword and sorcery, with just the right touch of antihero. I really liked what I read about the pact blade; sounds like a fun bit of flavor.
Thanks for the help so far guys, he's mostly built and ready to go.