I finished this wonderful splendid addon Flames of Vengeance just few minutes ago, and I couldnot resist registering here, little reading through the forum and seeing this Dual wielding question.
Ok, immediately I could afford it I bought "The mocking maul" and "Deodatus Mace" on the Great market, by Gina. Together with "Order of Viper" armour set this is quite deadly combination considering these weapons have some decent skill boosts that perfectly pushed up my warrior/mage skills. With charms and enchantments I have got at the end (in section antideluvial vault) this weapon damage: 388-738 + (1059-1456 magic).
Some other stats - main hand critical chance 62%, off hand critical chance 57 %, str 100, int 68, vit 91, Dual Wielding Expertise 13 (no trainer was able to raise cap higher

) The final fight with this dmg was maybe too easy though (in both variants), but on the other hand even more funny and satisfying :] as I prolonged a bit trying different skills, observing their effects.
Maybe its possible to achieve better damage with other combinations of parts of armour and skills but I didnot try yet. I can also note that I started with new character in FOV, because my old savegames from ED were unusable.