I was looking at the 1.09n weapon stats and dual-wielding actually fits very well within the damage vs. costs balancing they've got going now. I would suggest limiting dual-wielding to Clubs, Daggers, Axes, and Short Swords, at least to start out with.
The reason I say it works well is because (in 1.09n):
Gnarled Club - 3 Damage, costing 2 Gold and 3 Material.
Dagger - 4 Damage (+1 CbtSpd, +1 Accuracy, +1 Dodge), costing 4 Gold, 2 Material, and 2 Metal.
Staff - 5 Damage, costing 3 Gold and 4 Material.
Axe - 6 Damage, costing 4 Gold, 2 Material, and 2 Metal.
DW Clubs - 6 Damage, costing 4 Gold and 6 Material.
Short Sword - 7 Damage (+1 CbtSpd), costing 10 Gold and 4 Metal.
DW Daggers (+1 CbtSpd, +1 Accuracy, +1 Dodge) - 8 Damage, costing 8 Gold, 4 Material, and 4 Metal.
DW Axes - 12 Damage, costing 8 Gold, 4 Material, and 4 Metal.
DW Short Swords - 14 Damage (+1 CbtSpd), costing 20 Gold and 8 Metal.
Broadsword - 15 Damage, costing 18 Gold, 6 Material, and 4 Metal.
As you can see, the DW Clubs fits in line nicely in comparison with the single Axe and the Staff. The concept of actually dual-wielding clubs might be a little iffy though. Generally we expect our club-wielders to be untrained, not martial artists. With DW Daggers and DW Short Swords I think the Combat Speed, Accuracy, and Dodge bonuses should not stack. With that in mind, the DW Daggers works out nicely as well, making the Dagger seem like a more worthwhile weapon, if you have a Metal mine. DW Axes are a little on the inexpensive side. Not sure about that. DW Short Swords seems to work out quite well. So, IMO it appears far more feasible now than it did with previous versions.
Anyway, food for thought.