Hilt slashing, it's not just 2hers, it's any weapon. What happens is you do enough damage that you can hit extremely early in a release animation and not bounce, thus you hit "before" your opponent. You're not exactly faster, you're just able to utilize an earlier part of your swing due to how much damage you do.
If you are someone who doesn't turn into their swings, you're going to get destroyed by someone doing this.
tldr; It's not just 2h that can abuse this, it's any high str build. You simply have to learn what it looks like, and how to counter it.