Reposted from the feral DPS thread as I figure I'll get more answers here:

After searching around for conclusive answers to weapon skill, I came across this post on wowhead:

Shapeshifter's Signet - Items - World of Warcraft

(look at the comment by konra)

Summary:
Defense greater than FCS by 11 or more - Weapon skill grants 0.2% hit, 0.1% lower chance to get dodged, 0.6% lower chance to be parried, 0.2% higher chance to crit.
Defense greater than FCS by 1 to 10 - Weapon skill grants 0.1% hit, unknown chance to get dodged, unknown chance to be parried, 0.1% higher chance to crit
Defense lower than attack - Weapon skill grants 0.04% hit, 0.04% to be dodged, 0.04% to be parried, 0.04% chance to crit.

i.e. the first 5 points of feral combat skill are the most valuble against a lvl 73 mob, and the returns once you have equal weapon skill vs defense are extremly low.

This is somewhat verified here:
WoW-Europe.com Forums -> The idea behind weapon skill?


This appears to be the most complete explaination, and does not nesisarily contradict the previously known information on +def/+weapon skill. Essnetially breaking it down into a peicewise function based on the difference in weapon skill and defense, it incorperates all of the esstimated/quoted values for effects of +wep skill. It also fits in well with blizards mechanisms that drastically reduce your chances against a higher level mob (the penalties double if the difference is great enough)


This can also explain many of the differences found in hit% testing, where people got slightly off the expected results.

It also makes the Shapeshifter's Signet epic quality, if you aren't using any other +FCSR items.


Anyone else have any info on this?