Is it realistic to go for Dual Daggers?

And I don't mean just for the sneak atacks, I mean fighting completely with them. I haven't tested a lot but I don't really see that my daggers atacks consume less stamina than the other one handed ones, so I spend the same stamina for less damage, just faster normal atacks.

Also, do you think it is worth leveling one handed just for the sneak dagger atacks? I mean, what if I want to sneak atack with daggers, but once detected swing my 2 handed?

Depends. If you're not going strictly for stealth attacks, then any dual wield combination should be do-able.

Should work. There are very few combat options in this game that aren't viable, if you take the time to explore them a bit.

If you're doing only stealth daggers, then take the perks in the Sneak category. Got perks that increase your sneak attack damage up to 15x. 30x if you take the Shrouded Armor.
Nevermind. I just noticed that you're doing combat and maybe stealth.

Sneak Perk gives Dagger sneak attack 15x normal damage. So it is worth it for Sneak Attacks.

As for dual wield, dagger attacks much faster than sword, so if you have Enchantment on it such as Frost Damage, Shock Damage, Absorb Health, Paralyze, etc. then it is useful.

an Upgraded Dagger via Smithing is fairly powerful, just look at the base damage in the Smithing Screen. A dagger is around 8 then sword is 11, or if dagger is 17 then sword is 24. or something.

I got two deadric daggers as backup when my enchanted deadric war axes are depleted... The speed and dmg is insane. Id have a bow or magic spell for groups of high level magic casting enemies just to stay on the save side though.