The dadao is a beautifully modeled but, from my experience, very uncommonly used weapon. Stat-wise it's comparable to the miaodao but the miaodao is, for most skilled 2-handers with a good budget, the preferable choice. Compare:
Dadao
weapon length: 115
weight: 3
difficulty: 12
speed rating: 92
weapon length: 115
thrust damage: 0 pierce
swing damage: 42 cut
slots: 2
Can't use on horseback
5,226
Miaodao
weapon length: 115
weight: 2.8
difficulty: 12
speed rating: 95
weapon length: 115
thrust damage: 0 pierce
swing damage: 40 cut
slots: 2
Can't use on horseback
8,376
I'd like to see a minor change for the dadao, giving it either +1 damage or +1 speed. Conversely, the miaodao could be nerfed slightly but it seems better to keep it closer to other top-tier 2h-swords. With increased damage or speed the dadao could be more than a poor-man's Miaodao, as it seems to be to me, and instead be its own admirable brand of sword.
But I'd like to know what you think - as more experienced 2-hander players. Should more swords be closer to top-tier? Should the dadao be more unique or more similar to the miaodao? Or is everything working best with the dadao as it stands right now?