e: Until this post has received some feedback, you should probably hold off drawing any conclusions from it. I could always have made a mistake.
Most people know that WPF increases damage, and most people know that the damage bonus is 15% for every 100 WPF you go past 100.
However, I'm not sure if most people realize that the bonus to damage from WPF stacks multiplicatively (rather than additively) with the damage bonus from powerstrike. That is, the multiplier to damage is (1 + 0.08PS)(0.85 + 0.0015WPF) [source] (http://forums.taleworlds.com/index.php/topic,168722.msg4090900.html#msg4090900), assuming no speed bonus, hold bonus, or sweetspot penalty. I was running some numbers, and this actually leads to a surprising increase in damage.
The following is a table that plots the effective damage for 8-conversion level 30 melee builds with maxed WM, vs the damage bonus for builds with both 0 and 3 WM. This is assuming no WPF penalty, so heavier armor will drastically affect this.
For example, a build with 111 WPF would need 5.68 PS to do as much damage as a 4 PS build with 180 WPF. Also, a 3 WM 15/27 build will actually do slightly less damage than a 9 WM 12/27 build (with light armor).
Some of the WPF values may be a bit off. I remembered that 0 WM is 111 WPF, 3 WM is 130 WPF, and I believe that 9 WM is 180 WPF. For the rest of the values, I used the calculator.
If I have made any errors, please don't hesitate to correct me.
e:
It occurs to me that I didn't include the strength/5 bonus to damage. However, this bonus is simply added to the raw damage prior to calculating armor reduction, so it should be very tiny compared to the base damage of the weapon multiplied by all the modifiers.
I'm not actually sure if WPF reduction due to armor affects damage, or if it only affects swing speed, accuracy, and PD/PT requirements. I would guess the former, but I've never actually read anything to that effect.
It's worth noting that speed bonus, hold bonus, and limb damage modifiers also all stack multiplicatively. So if you've got a really high ath high WM build, you can deal out some serious punishment with high speed bonus held head hits. It won't be as high as a strength build doing the same thing (probably; the duel server doesn't print out the speed bonus of hits, so I'm not sure how high that gets), but it's a lot easier to line up those hits with more ath.
So, I now wonder what PD/WM combination does the most damage. Either way, they all do comparable damage...
@ 30
15/27
18/24
21/21
24/18
27/15
If WPF reduction due to PD affects damage (I would guess that it does), then this chart should be accurate:
If that's not the case, then this chart (http://s13.postimage.org/yw6j6ni2f/rangedchart_A.png) should be accurate.
Either way, it looks like higher PD builds do more damage. On the other hand, the difference isn't all that pronounced, and the lower PD builds are going to be vastly more accurate. I'm not sure how (if it all) WPF affects damage dropoff due to decreased projectile speed at range.