2d10 for single wield (e.g. greatsword, maul) to make more fair against dual wielding. Dual wielding weapon eg pike 1d8 plus battleaxe 1d6 is already higher than 2d6 for greatsword not to mention the 2x str/dex/int gained or 2x damage from ice/thunder/fire/fine/exceptional from two weapons.
Maybe to make more fair also can have 2+ str/dex/int per greatsword weapon to compensate too?