Obviously lighter weapons swing faster than heavier weapons, I thought. We know that daggers swing much faster than swords, and swords swing much faster than two-handed greatswords. I just didn't know how much faster. So I decided to do a quick test and was surprised by result.

Skyforge Steel Sword weighs only 10 and does 11 damage.
Daedric Sword weighs 16 and does 14 damage.

So this is a huge 60% weight difference. Surely the difference would be noticeable.

So, I measured how many regular swings I could do in 1 minute.

Both swords did 69 swings in one minute. I was pretty surprised. I was going write something about how Skyforge Steel weapon swings much faster than a Daedric Sword, but no. Do weapons in same class hit at same speed?

I'm too lazy to do it now but I may test this at some later time. Unless this is something everybody knows already. Is there any place with DPS data for weapons?

Yep, you can look it up on the wiki, such as this list: http://uesp.net/wiki/Skyrim:Iron_Weapons#Iron_Weapons

All weapons of the same class have the same speed as the iron weapons listed there, with only two exceptions that I've found:
The ebony dagger is bugged and have a speed of 1 (instead of 1,3)
The Longhammer is 30% faster than a normal 2h mace - http://uesp.net/wiki/Skyrim:The_Longhammer#The_Longhammer

The attack speed of a weapon is a set value in the game, but a few weapons are faster by design. The Longhammer is an example of a weapon with a faster attack speed than most other two handed weapons in the game.
Wieght does affect the Stamina drain of a weapon, especially for using Power Attacks.

Well wiki needs to update cause one of the keynotes of 1.5 was fixing the Ebony Dagger atk speed. Me and another forum goer tested it and it does swing like the other daggers (finally).

You said 69!

OT It was probably one of those details overlooked due to the necessity to release the game on a catchy date. sarcasm/

Wow thanks guys. I keep learning new things about this game.