I definitely favour dual wielding. Enchants 'cross charge' - e.g. put +100 magic damage and +100 physical damage on both your dual-wield weapons, and EACH weapon will get all the bonuses: +200 physical and +200 magic on each weapon, or +800 damage bonus in total across both weapons and damage types. Dual wielding effectively doubles the value of each +damage enchant, and it doesn't even matter which weapon the enchant's been cast on!
That has BUG written all over it 0_0.