Swing at you 2h's max range. As he blocks the fist swing: stay at that range and immediately swing again. Use footwork to make him miss his swing as your swing just hits due to it's superior range. This is easiest and very effective, especially with the longer weapons like greatswords. (Kite-spam)
If you're a good manual blocker, you can also try to facehug him and try to get behind him. This is relatively easy to do and quite effective.
Some shielders fall for feints. Try one or maybe two. If they don't fall for the first feint, beware. They will counter by spamming you, thus hitting you while you're feinting.
And lastly, like marathon said, try holding an attack just a bit longer. Good shielders release their block instantly after you hit. By delaying a swing a bit (holding it a bit longer), you can make them release block early.
Some shielders are very predictable in their swing directions. If you have practiced this, you can try a chamber block. I'm mentioning this because it's possible, not because it's the smart thing to do though. But some situations allow you to chamber. Sadly, most alert shielders don't fall for a chamber block counter. Some do though.
To sum it up, there are several techniques:
- Kite-spamming
- Facehug / get behind
- Feinting
- Holding
- Chamberblock
The trick is to guess which approach works best for your opponent.
