I killed bjord in a fair duel, while he was using his triple heirloomed GGS and I used a regular knightly heather shield and a regular katana.
I spent more or less an hour on the duel server accepting all duels and requesting duels to everyone using the same shield and regular :
- morningstar
- mace
- HBS
And did okay. Probably because their was about 80% of nonames (yet no peasant or complete noob either)
The shield did not break and I always used it together with the bastard weapons.
Now, it is true that the 1h mode of all these weapons is complete garbage. In real battle it's only useful on horse for the long ones (aka not the mace) and success in duel mode with this type of weapons only happens because they are unusual and even the best are not prepared. I'm just an over average shielder like dozens of others so it is more linked to the surprise effect than my incredible skillz.