Take a Blade's long sword, and an iron war axe. The Blade's sword is obviously longer, but in combat, can it hit enemies from a further distance? This also applies to two handed weapons.

Has anyone tested this?

It seems to work that way for NPCs, but not the player character.

Using 2-handed warhammers I've noticed my range is very long, at least compared to 1-handed maces.

I don't think it is a factor during combat.

I sure hope it does! I will test it out a bit later

The longer the weapon, the longer the attack range.

I've used a lot of one handed and two handed weapons and although i don't find a difference between the one handed weapons or two handed weapons on their own, there certainly is a difference between one handed and two handed weapons. For example when you've mastered one handed and/or two handed you can pick the perk to potentially paralyze the enemy if you do a power attack while moving backwards.
With one handed weapons it's nearly impossible to hit an enemy with such a power attack because when you walk (not run) backwards while charging the special attack you miss nearly 90% of your strikes. It only hits when the enemy itself is performing an attack at the very same time so that he's moving towards you.
With two handed weapons this is done much more easily. You can walk back and you'll hit pretty much anything that's remotely close to your character, even if he's not performing an attack and thus is standing still.

Therefore i'm nearly 100% certain that two handed weapons have a longer attack range than one handed weapons. I can't confirm this, but it feels like it.

My greatsword has longer range for sure than my 1h sword. I can start power attacks a foot or more earlier with it. When I switched over to dual wielding I kept missing with power attacks because I wasn't getting in close enough anymore.

I'd say definitely yes, at least between 2-handers - 1handers - daggers. I used a dual-weidling sword and dual-weilding dagger attacks, and tbh the daggers often just plain didn't reach the enemy. Same if you mix a sword and a dagger, for example - sometimes you'll do full damage, sometimes the dagger will be out of reach and only the sword hits will count.