This thread is both request and idea.

Currently, Skyrim has 1-hander/shield ("sword and board"), dual wield, and 1-hander melee combat types. IMO it would be nice to see more options and rebalancing, with each combat type fitting its own niche.

Dual wield: Already balanced (and overpowered with destruction enchants and -100% cost set). No change.

What it's good at:
+Hammering one enemy with maximum DPS
+Stacking dual destruction enchants with -100% cost armor set. Particularly dangerous in a dual wield battlemage build.
+Dual wield power attack.

What it's bad at:
-Defense (no blocking or parrying)
-Area damage
-Stunning/staggering (no bashing)
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1-hander and shield: Already balanced. No change.

What it's good at:
+Stunning enemies. Knock them down or bash them with a shield
+Defense. With proper perks, you can negate arrows and halve elemental damage.

What it's bad at:
-DPS
-Area damage
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1-hander with nothing in the off-hand. New combat type focused on timed parrying and counterattacks. Add one-handed talents for counterattacks: If you time a parry just before getting hit with a melee attack, your character counterattacks. Perks increase counterattack power, and there could be a perk that lets you parry arrows. The Dual Flurry perk would also give +15%/25% faster attacks if you are using a 1-hander and no shield. There would also be a perk that gives a one-handed sweeping power attack with empty off-hand (with a significantly smaller area than the 2-handed version).

1-hander with no off-hand versus "sword and board":
+Much better DPS - faster attacks and counterattacks
+Sweeping area power attacks
-Lower defense (no shield)
-Lose out on elemental resistance perk and shield charge knockdown
-Bad against archers - unable to stop arrows until higher skill levels and even then it requires a timed parry.

What it's good at:
+Single-target DPS, particularly against melee
+Blocking and countering melee attacks with no need to throw perks into Block
+Limited area damage

What it's bad at:
-Blocking arrows and elemental damage

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2-hander and shield (on an arm strap).

Allows for both area damage and shield blocking, with significant penalties: -30% block effect and armor from shield; -20% global damage multiplier, and -10% slower attacks.

New perks:
-Arm Shield: Block and armor penalty from using a 2-hander with a shield decreased to -15%
-Mighty Grip: Decreases global damage multiplier penalty to -10% and slower attack penalty to -5% when using 2-hander with shield.

The main reasons to use 2-handers with a shield: Area damage and extra defense against melee (stay out of reach while also being able to block)

What it's good at:
+Defense combined with reach
+Area damage
+Blocking
+Stunning/bashing

What it's bad at:
-DPS.
-Stacking with destruction enchants
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Buff 2-handed weapons. Make them significantly faster (although slower than a 1-hander) when you have no shield equipped. Also give them more area damage.

Perk changes:
-Sweeping power attack talent now gives all two-handed attacks (with no shield equipped) the area damage. If you are using a shield with a 2-hander, it enables the sweeping power attack instead. This would make 2-handed weapons actually useful, giving them a specialty in area damage.
-All characters can now do two-handed sweep attacks (with no shield equipped) even with no perks.

I have one character specialized in 2-handed weapons and they just plain svck in vanilla. They're slow so they can't apply enchantment damage quickly, they prevent you from using a shield, and they're just clunky and unwieldy in general. The only reason I can think of for specializing in 2-handed weapons is AoE damage in an archery/2-handed build (use the 2-handed weapon for AoE damage on the sweeping power attack). These changes wouldn't make 2-handed melee overpowered, dual wield with dual destruction enchants would take a dump on their DPS anyday.

What it's good at (after buffing):
+Area damage. Especially with the updated perk that gives all 2-handed attacks area damage while you have no shield equipped.

What it's bad at (after buffing):
-Defense. Nearly as vulnerable as dual wield, except that you can bash and parry.