Seriously am I missing something here? I've hopped on duel plenty of times with a good ol' Great Maul for lulz, usually against clanmates, and it wrecks shit. All you need to do is block 1 hit, just one, their weapon gets stunned, and you go overhead, and then you can just keep overheading until they have no visible face left. I don't ever side swing with the maul....and it did wonders. Though keep in mind, when I did this I believe it was +3, so that might have affected the weight so maybe weapon stun from blocking isn't normally that prevalent or something? Because I can't see why people don't just block then overhead. It's ridiculously easy.
Your weapon does not get stunned if you are the attacker.
If you are defending, you will only be stunned if the attacker has a heavier weapon and/or more strength AND the attacker is using held attacks.
As most weapons are much longer than a great maul, you can hit them without even getting close. If the maul user is using held attacks, you can hit them first if you have a really fast weapon. As far as blocking side swings, it moves so slow that it's terribly easy to block.