movement speed, shields are heavy
You still are a lot faster then a mauler. As said before, maulers are
str oriented builds in
heavy armors (most of times) with one of the
slowest weapon (and
shortest beside longmaul) and it's
unbalanced!
The crushtrough factor is balanced by the fact that the maul user really is really slow (both for swinging and footwork) and he can't feint either!
You got there an easy spammable target.
Most onehand weapons are longuer so keep him at distance, dance around him, feint and spam! By the way, it's easier to do with ur shield on ur back cuz u walk faster and u swing faster. This is a tip coming from an ex-lol-greatmauler so I know exactly what I'm talking about.
If you cry about how they are OP in tight corridors in siege, well, that's the only place they are "OP". Go play battle, I'm sure you won't find any mauler on battle, he'll get raped by cav and archery before he can reach a shield wall.
Back on topic, I have not played much siege lately so I can't know for sure what is happening with shields when you try to block a doorway.