I'd say shield > 2h > 1h for blocking effectiveness(how often you get staggered and such). Since you have both hands on a 2h it does make sense that you can take more force blocking with it. If you use a 1h weapon to block a powerful swing with a 2handed weapon you should be asking for problems.
They could even get around the control issue, just make attack = parry/block with 1h if you time it to respond to an enemy swinging.