A small note (January 2019)

Greetings! I've logged in to nexus for the first time in about five years and I'm quite happy to see that people seem to like this mod and still download it. I've received a couple of messages over the years of people asking for permission to integrate it into their own mods and so on. I'd like to say sure, go ahead.
It's great to see how Skyrim is still so popular even after a couple of years. Cheers to the games we love!

What this mod does

This mod aims to make two-handed weapons a more viable option, by adding perks that allow you to increase attack speed as well as improve blocking.

"Swift Strikes" has two ranks and will allow you to attack up to 30% faster with a two-handed weapon (Alternatively, there's a toned down version that some people have requested, which will add only 20% attack speed)
"Defensive Stance" has one rank and improves your blocking with a two-handed weapon by 30% (Toned down version: 20% better blocking and perk requirement is 60 2H skill instead of 40)


Reasoning

Two-handed weapons scale very badly with Enchanting and Smithing bonuses.
Enchants and weapon tempering apply the same fixed bonuses to any weapon, regardless of their attack speed. This means that a faster weapon will benefit much more from said skills, because it can apply the damage bonus more often.
With 100 Smithing, 100 Weapon Skill, as well as Armsman/Barbarian Perks, a one-handed Daedric sword will slightly outdamage a two-handed Daedric Greatsword. That is not even taking damage enchantments into account, which would widen the gap even more in favor of one-handed weapons. (Keep in mind, I'm only talking about a single one-handed weapon here, not dual wield!)

In the end, two-handed weapons are unwieldy because of their low attack speed. They slow the user down while he's attacking, practically negating their range advantage, they use a lot of stamina to execute power attacks because of their weight, and nevertheless they WILL be outdamaged by a single one-handed weapon eventually.

To address this, I've added a perk that gives the player +30% attack speed with two handed weapons (split up into two ranks with 15% increase each). This will increase the average damage output, allow two-handed weapons to benefit from smithing/enchanting much better and also help with defending yourself, because you can go back to blocking, bashing or evading much earlier, and won't be stuck in an attack animation, which can be quite frustrating.
Overall damage will still be lower than that of dual wield, as it should, but higher than sword and board. Your attack speed with a Greatsword will be at about 0.9, so it'll be a little bit slower than a one handed sword.

The new "Defensive Stance" Perk (at 40 2H skill) allows you to block 30% more damage while holding a two-handed sword. Blocking enchants, on necklaces and such, don't work for two-handed weapons, so this Perk will provide you with a better defensive option, to compensate for the lower damage compared to dual wield. Defensive Stance will stack with Shield Wall from the Blocking Tree.
Of course, Shields will still be much better for defense because of their option to be enchanted, and perks like Elemental Protection.

These new perks will make two-handed a good, balanced option if you don't want to go full on offensive mode with dual wield, but don't like hiding behind a shield either. The inherent drawbacks of two-handed weapons are still there: You'll slow down to a crawl while attacking, and you don't have the flexibility to quickly switch out your offhand. (Consider that someone who goes sword/board can still just pick the dual-wield perks and switch out the shield for another weapon or even a spell at any time. If you go down the two-handed route, you're commiting to that playstyle.)
In the end, I think this mod will buff two-handed weapons pretty well, without making them overpowered.
Of course, if you have any ideas or thoughts, make sure to leave a comment. If you like it, feel free to endorse and help the mod being seen.

Notes

Install via Nexus Mod Manager, or just put the .esp in your data folder.
Shouldn't conflict with anything, except of course other mods that change the two-handed tree.

If you want to uninstall after having picked one of the new perks, I suggest that you use the console to remove the new perks first.
Type in "help swift" (without quotes, obviously), to get a short list where you can see the code of the perk. Then just enter "player.removeperk" followed by the code for the perk. Do the same thing for defensive stance as well, if you have that perk.
Check if the perks are removed properly and save the game in a new slot. Afterwards it should be be safe to remove the mod.

Please note that Elemental Fury does NOT stack with Swift Strikes, so you won't notice any effect while using the first level of Elemental Fury (30% Attackspeed increase). The full shout will give you 70% increased attackspeed.

Another alternate version was done by Layam:
http://skyrim.nexusmods.com/downloads/file.php?id=14741
This one will reduce the damage bonus gained from the Barbarian perk by 5% per rank. If you feel that the overall DPS with 30% increased attackspeed is too high, but want to keep the increased flexibility of faster swings, you can use Layams take on the mod.

There's also a Spanish version available, made by Aegeons:
http://skyrim.nexusmods.com/downloads/file.php?id=11910
and a Czech Version, too, which you'll find among the downloads. Thanks to GrimReaperCZ for translating.

Version History

1.01 - Fixed a little bug that would make the Elemental Fury Shout more than double the attackspeed, when used together with Swift Strikes.

1.0 - First release, duh...