This is definitely something we’re keeping a close eye on. Dual wielding has only been in the game since December and the dust has only recently started to settle on the state of its balance compared to 2h weapons. It certainly looks like 2h weapons are underpowered at the moment and you can expect buffs for them in future patches.
One thing to keep in mind is that we’re still in the process of redoing our item base types, with shields, sceptres, and relics being overhauled this patch. With each of these base type reworks we plan to introduce multiple viable base types for end game and often these base type are more powerful than their equivalents pre-rework, especially for builds that can take advantage of their new secondary/niche stats. This sort of rework hasn’t happened yet for any two handed weapon types and when it does they will inevitably increase in power.