Because dual-wielding daggers are impratical in real life.

Okay, so here's the ordeal:

When thinking this: I simply thought of nightblades. You know, assassins with spells and stuff?

See, that's the whole idea. Here's a link: http://skyrimcalculator.com/#242515

Here's how I explain my choices:

One-handed:

-Armsman, Fighting Stance and beyond: More damage, less stamina spent, chances to instakill and paralyze someone. Seems straightforward.

Light Armor:

I took all the perks mostly because it's a must when sneaking.

Sneak:

Being a spellsword/assassin hybrid, it's a no-brainer on this one. Though it svcks that I need to take Deadly Aim for Assassin's Blade.

Illusion:

-Quiet Casting: Silent spells, yay!

Restoration:

-Respite: My healing spells can be used to restore Stamina.
-Regeneration: Boosting healing spells helps.
-Necromage: Why is that one checked? Because my planned character will be a vampire.
-Ward Absorb: Wards > Shields.
-Recovery: Regenerating magicka 50% faster can come in handy.

Your advices?

I find wards to be quite useless, if you can use them go for it.

Depend do you consider short blade as sword or dagger.

There are some Asian martial arts that have dual wield dagger or short blade that is so short that you may as well consider it as dagger.

So I won't say it is impractical