In short, how do you do it and is it worth fully upgrading? It sounds useful (and cool) and I can certainly imagine archers being a pain in the ass, especially if they "twitch" Geralt out of his block stance. On the other hand, I've played enough RPGs to know that sometimes the skills that sound cool are actually crappy for one reason or another, or that there might simply be hardly any archers in the game (kind of like learning anti-undead skills in an RPG where the undead are in it for only one small part).