Since you're talking about low levels, I think that swordsage could be a good options.
Weapon Finesse + Shadow Blade = Dex bonus on attacks and damage (and, unlike CoC Elegant Strike or Swashbukler Insightful Strike, no immunity to sneak attacks or critical hits can prevent that bonus damage).
You can also use Revenant Blade: with the capstone legendary force, you can treat both ends of the Valenar double scimitar as two-handed weapons, even when you use it as a double weapon. I think that's the best choice for a two-weapon fighter.
Warblade + Revenant Blade could do wonders: at medium-high levels Tiger Claw can grant things like additional attacks and pounce.
