If you have the 110-140 WPF or whatever, how much will a couple weapon speed (from one weapon to another) actually be evident in combat?
For similar animations, I believe that the "total" weapon speed difference of 2 or more is quite noticeable. The speed difference needs to be slightly larger depending on how much longer the other weapon is. When I was using 99-100 speed weapons, I noticed that I was getting beat to the punch more often in terms of swings against those who I believed were pure builds. When I switched to a 103 speed 88 length weapon, with 130 wpf (~100 effective with armor mitigation), it of course decreased dramatically. However, pure 1h builds in light armor and 100-101 speed weapons still managed to swing at similar speeds to my own. 1h right swing also lost out against much slower weapons, but when I tried on a 15/24 with 172 wpf, it was much faster.
In general:
Every millisecond counts. You want high speed, but there is typically a cutoff point where the speed is acceptable. It makes it harder for the enemy to hit you without even better positioning, especially when the swings are nearly concurrent. It makes the weapons that were slightly too slow before (for 1h, that is around the 97-98 speed mark) to compete with users of faster weapons. If your wpf brings your weapon speed +2 above the average, 97->99, you would be able to compete in speed against any other typical 1her that doesn't have very high wpf. Less caution is needed and you can be more confident in your swings when the other player releases a swing.
There are so many different factors, it's difficult to answer your question without bringing up more factors.
- Whoever moves faster can give themselves optimal hitting angles easier. Weapon speed and higher movement go hand in hand. Moving away from an opponent's swing gives you precious milliseconds to get your own swing off.
- High damage makes it easier to swing earlier in the animation. Since the windup is only a fraction of the animation, small weapon speed differences aren't too noticeable.
- Weapon speed greatly helps the slower animations. Animations differ on their speed for windup and release. For instance, 1h right swing has a somewhat quick windup, but a poor release. Polearm stab has a pretty good release. The fast animations typically beat out the slow animations even with decent weapon speed differences, but weapon speed helps normal-speed animations win out over faster ones, and slow ones win out over medium ones, especially when different reaches are involved.
- Longer weapons at weapon length can make do with less speed. Decent speed weapons with good reach are typically more valuable than short, but fast weapons. It is why the longsword is more popular than the HBS, it already has great speed, and the weapon length makes it excel further. The lower the speed, the more one has to rely on those early hits.