So I don't know if this is really explained in detail somewhere already. If so someone point me there.

This was Skyrim only but, I played as a sneaky mage. Now, I used light armor and a one-handed sword with spells in the left hand. It was soooo much fun that I'm really hoping that I could do something like that in ESO. I've seen the siphon stuff for the Nightblade and what-not, but that's not really how I played that version of the character. It was extremely glass cannon when I got caught, but the magic still let me put up a fight. I was just kind of wondering if this is going to be possible in the online game.

Every class can sneak, firstly.

Secondly, you will not be equipping spells to your right or left hand like in Skyrim. You can equip staves (destruction or restoration-based) but those are two-handers. Spells will be insta-cast however using the number keys 1-5 and 6 for your ultimate.

Thirdly, playing with just one one-handed weapon is possible, but likely to put you at a disadvantage since there are no skill-lines that support it. The melee skill-lines are Dual-Wield, Two-Handers and 1-Hander+Shield.

So it won't be totally the same, but it will be similar.

I plan to be a Nightblade who wears robes and carries a two-handed sword and backup Lighting Destruction staff, myself.

Yes, no need to have spell in left hand so you will either use an shield, a second weapon in left or a two hander.
Not sure how just one weapon will work, I guess it will count as two weapons but with reduced damage.

And yes everybody can sneak, sneak also work against enemy players. Nightblades are better as they has a dedicated sneak skill line.

I did not test out sneak much in the beta, in short I did not think about sneaking as you can not sneak in most MMO unless an thief class character.

Well clears that up.

Guess you could dual wield and do it too...hmm, that's sounds better then my original character actually.