I've always been a huge proponent of + dagger skill amongst the rogues in my guild but they never believe me, but thats another story. However, right now I am wearing +11 dagger skill from ACL and Circlet of Restless Dreams (which is out of reach of most rogues because the pain in the ass to get a dragon kill let alone it dropping).

I was running a mod that parses my glancing blows. It would tell me the percent of white swings that were glancing, my average non-crit non-glancing and my average glancing blow and compare the difference and then give me a theoretical amount of white damage that was lost due to glancing blows. (The mod was taken off the WoW forums from some thread that I don't remember).

Assuming the mod isnt buggy here is my question:
On the drakes in BWL with +11 weapon skill i ended up **GAINING** damage in my glancing blows according to the parser.
My first assumption was that windfury/totems/battleshout weren't always up so my attack power wasn't constant and this would throw off any averages in such a small data pool.
On ebonroc and flamegore I made sure that my AP was constant so there would be no changes and still managed to get a very slight increase in glancing blow damage over regular white swings.

I've always assumed this was impossible but the only thing I could think of is that:
1) The presence of glancing blows is based upon your level, not the difference in weapon skill vs defense skill. This way no matter if you had +200 dagger skill vs a 63 you would have glancing still.
2) + weapon skill merely reduces the mitigation of glancing blows and enough of it would push you over into a bonus, a "crushing" blow.

If anyone had any data or clarification on the possibility of actually gaining bonus damage from + weapon skill as opposed to merely mitigating glancing blows it would be appreciated.

With that said I'm going to go to DM and get muggers belt + distracting dagger and buff myself up to +22 dagger skill and go fight an elite in silithus and hand parse the data. See if I can come up with anything.

This is discussed in another thread around here. Basically, the effect on Glancing Blows does end at +10 skill. Your glancing blows appear to be bigger at that point, because they can't get blocked, whereas normal hits can.

While I'm too lazy to link you the other thread containing relevant data reports from various people I will give a brief summary of the findings.

It works as weapon skill vs mob defense ie. for 60 vs 60 its 300 vs 300.
The optimal / best amount of +weaponskill to get is 10 assuming you're fighting a level 63 mob anything lower makes the +skill less valuable. Muggers / ACL is currently the best combination, assuming you dont have a shot at death sting in the foreseable future, if you are then you'd probably also be able to drop muggers for belt of never ending agony.
It is a 3% damage increase on the glancing blows per skill point. Meaning a 30% total.

+22 weaponskill would be complete overkill you'd never fight anything with high enough +def to make it worth the sheer scale of gimpage you take for it. Gaining +10 weapon skill gives you +.5% hit and +.5% crit, which isnt a viable way of gaining hit/crit but its an addition none the less.

Assuming a 17/24/10 build. You'd still have a large gain using a seal fate build on white dps but since seal fate isnt as white damage oriented the gain would be substantially smaller.

Edit.
http://forums.worldofwarcraft.com/th...readID=1051138

This is the direct link to the official forums. Ra - You can do the maths yourself but yes they're better.

you really think ACL + muggers is better then ACL +circlet of restless dreams (21 agi 38 stam +6 daggers)?

Run em through the combat dagger spreadsheet :)

UPDATE: For my level gear, that helm provides 2 less DPS (raid buffed) than running muggers and bloodfang.

Here you go... it is discussed alot more indepth here:
http://forums.elitistjerks.com/viewtopic.php?id=6457