I've only encountered one person doing this and I've been around since beta. I would tell people not to panic or start accusing every good manual blocker of hacking. Like it or not there are people who have played this game for over a year and have done so at a high level play and they are very skilled blockers. It takes repeated behavior and a very good understanding of what is possible in the combat system to accurately accuse someone of hacking, and, unless you have played this game extensively, I would say the majority of people are woefully illequipped to distinguish an expert manual blocker from a hacker.
I apologize for the condescending tone of this post, but rumors and baseless accusations should be headed off as soon as possible for the good of the community.
I'm going to assume this was directed at me. If not, I apologize.
I'm not one of the top players in this game, but I'm good enough to judge whether someone has skill after fighting them for about 5 seconds. Not to mention the NA community isn't that large and I've come to recognize the really good players.
Someone that can block a dozen of my attacks in a row despite all sorts of feinting and general slipperiness, and yet can barely manage to land a strike on my shield because their timing is so bad is certainly suspect. Especially if there are two of them, they both have generic names like Bill and Tom, and they manage to die despite their matrix like reflexes because they can't prevent me from getting behind them.
I've played other online games that went entirely to **** because of cheaters. Whether or not you've only seen one cheater since beta is irrelevant. The hack is out now, I actually heard about it on the Steam forum first. More people are going to use this, because a lot of people are assholes. Until someone manages to counter it, it's going to be a serious detriment to the game.