I′d say Illusion or Conjuration. If you face several enemies, it can be quite useful to calm several of them to take them on one vs. one. Or as the others suggested, Conjuration. Having a friend or several backing you up is quite convenient, not to mention Soul Trap.
Or you can combine the Ebony Mail with a Cloak Spell for nice damage while doing nothing...

Good point! There is nothing quite like engaging a powerful mage in a battle, jumping into a side passage to avoid his ice storm, jumping back into the main passage, using the wind sprint shout to close the distance in an instant, shield bashing him in the face before he can get another spell off to stagger him, then before he recovers running him through with your bound sword for the kill animation.

I'm a 2h warrior mainly but I also use a bow, and I'm skilled in restoration and destruction as well. Works really well for me.
Restoration is most important though, since you get hurt a lot in battle.

I don't typically wear a helmet either. Once my heavy armor skill hits 70, I plan on investing four perks to get the weightless armor so I can take another stone. But since I don't get hit that much, it could take a long time to get heavy armor up that high.

As a 2H class you have to consider what your weakness will be and what school will help counter that. Also, remember you have to pause and switch between spells and swordplay if you use 2H. Here are my thoughts.

Destruction - Obviously you wouldn't need it for melee damage, so it's only useful at a range. That means you're not getting the optimal use out of the magic school's design. A bow however is designed to be purely range based. So this is a much better choice for that type of damage. Add a few points in the tree and the stealth perk, and you can get lethal with a bow pretty fast.

Illusion - The primary benefit from this school is crowd control and quiet casting. The problem is, as you level, you have to put points in the perk tree to get continued benefit against higher level foes. What good is a fear spell that only affects low level creatures when you can one shot them? So unless you spend the perk points, this won't be as helpful in boss fights. Invisibility seems like a nice spell, but you can easily make potions instead.

Conjuration - I hate pets. They get in the way as I flail around with my mighty blade. True, you can eventually summon some awesome pets, but you can also have companions with you as well. If you can't make it through a dungeon with a companion, your build needs more work than a simple spell school. It's really up to you, but the "benefit" of a companion is available for free from the many people who will gladly fight with you at no cost of perks (Though I'd love to see a perk tree for leadership).

Restoration - This school has a bit to offer a melee fighter. Healing can benefit a great deal, especially early on. However, with the surplus of potions available, it's not a MUST have. Increased magic regen isn't that big a deal since you won't be casting too many spells in the first place. Avoid death is a nice get out of jail free card. However, by the time you get 100 in restoration you will be loaded down with Ultimate Healing potions. You can chug one of those without having to switch weapons, so it's also not great.

That leaves my choice for a melee compliment ... Alteration.

Alteration - This has the best perk for a true melee class IMHO, Magic Resistance. It costs 5 perk points, but you block 30 percent of a spell's effects. You can also spend three more points and get Atronarch once you hit 100 in alteration. Alteration also has some very helpful spells like Detect Life, Telekenesis, Paralysis, Transmute, Equilibrium and Water Breathing.

Therein is the whole problem with that plan, and why sneak demands light armor

I think if I had to make a potion for every time I used invisibility... i would need about 5000 potions. These two do not compare.

I know. The things I will do for vanity. The dunmer just looks good in iron, and I suspect he will look equally good in ebony (Daedric just looks too weird). I got the idea for a dunmer from a post Farrington made about Divayth Fyr being a Telvanni mage that wore heavy (Daedric) armor, which was one of the reasons I started about making a dunmer spellsword.

Muffle and the muffled movement perk should help with that though. should still be fine. I wasn't talking specifically to you about that issue with heavy armor. It used to be a well used argument in favor of heavy since you could make its weight not matter and therefore be equal to light. The problem is of course, that you have to wait like 30 levels to do so, and... that is the game!

The other trade-off between heavy and light is you give up the stamina regen perk by going heavy but you pick up the perk that lets you fall twice as far. The stamina regen perk for light armor is probably more useful but being able to fall twice as far could have some good roleplaying uses for a light-on-your-feet nightblade.

I made a two handed spellsword breton child named Dovakid and I play on master with PISE v81 with harder creatures pack, Deadly Dragons hardcoe, and War in Skyrim.

For magic schools I went with:

• Alteration perks: Novice Alteration, Adept Alteration, Magic Resistance 3/3
  
• Conjuration perks: Novice Conjuration, Necromancy, Dark Souls and Twin Souls
  
• Restoration perks: Novice restoration, Respite, Regeneration, Recovery 2/2

I went with heavy armor as well, but looking back on it, I wish I had taken light armor instead.
I do 50/50 magicka/health though. I make up for stamina with enchants and respite.

Full Build: http://skyrimcalculator.com/#82237
Results: http://youtu.be/z9nX7QRjm7c

Totally, I wish we had that on light, not heavy. I do not understand how it makes sense it is on heavy at all, but I guess they needed something. Although I doubt many people even care about it

Right now I just have to use etheral shout all the time so my little hero of dragons doesnt hurt his ankles..

2hand 1hand
o of little skill.

shout shul shout whatever.
pathetic fool.

I just didn't figure a 2-H build would be too concerned with being invisible on a regular basis. It really depends on the play style because to use invis regularly requires some investment of character potential.

Invis requires 334 magika. A 2H build likely will not have that much of a mana pool. That means four points dropped in illusion to get that cut in half. Also, once the higher levels are reached, additional points have to be spent in the illusion school for it to remain effective. That's a lot of grinding and perk points spent for a spell that is situational. I don't use illusion spells with melee characters, so it wouldn't make sense for me. By all means, if you're using other spells in the school, it would be crazy not to utilize it.

Again, if someone wants to rely on invis then they might reconsider a 2-H build.

There ARE a few other options to the invis spell. There's the Shadow Stone which offers invis once a day. There's a faction quest reward that can also give invisiblity daily. Potions. Of course, there's stealth. But that also requires a significant perk investment to get the maximum benefit. The beauty of Skyrim is that there are many ways to achieve the same effect.

you're right, for the 2-hand you will want potions

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