I'm no expert at this game, so correct me if I'm wrong, but it seems that Dual Wield provides more benefit than other weapons, even for spell casters. This is because a weapon in each weapon slot gives more weapon/spell damage than weapons that take both weapon slots (with equal level and no passives). Having two weapons allows an additional trait for sets, an additional enchant, and the final passive in the dual wield tree even grants 5% damage (if wielding swords) on top of that. This is not a complaint about dual wielding though, but rather a lack with other weapons.
What I'm proposing is that new offhand items be added to the game that compliment the weapons listed in the title. Examples include a scabbard for two-handed weapons, quiver for bows, and spell book for staves. All three of those can be shown on the back, too, which is neat. Either these offhands can provide no damage, but just allow an additional trait and enchant, or the weapon damage on these weapons can be lowered to be in line with one-handers, with the offhands granted equal damage. I believe this would better equalize all weapons.
I suppose this would take a lot of work, and so it's not likely to happen. Also, people don't seem to like my ideas. But I think it would be cool. It'd allow magicka users to use a staff instead of dual wield and still get that extra bit of spell power, along with the extra trait and enchant. Plus the benefit of ranged light/heavy attacks for ultimate building and resource return. The biggest thing here is the additional trait for sets though.