First off, this skill stacks up to 5 times. End result, +1000 parry rating, 3000 damage on next parry.
Now, the trick for DK's with this for DW is the fact that it can proc off all of your normal white weapon swings, your plague strike swings for both hands, your blood strike swings for both hands, your obliterates for both hands, your frost strikes for both hands, as well as your rune strike. So, unlike a warrior or paladin who only should expect to see an average of 1-2 with a high of 3-4, a DW DK can expect to see an average of 2-3, a well as a significant increase in your single target threat on top of things.
I do use the simple avoidance meter i got from curse called...... "avoidance", and I track my progress. Going in with DW Legacy of Thunders, I have 27.63% dodge, 18.04% parry with horn. My total avoidance at base reads at 56.60%.
Now, I do have the new Sigil (even tho it says chance, it has a redic procrate and is almost always up. This in essense is what allows DW DK's to stack so much more of the BW stacks. When the sigil procs in a raid setting, I usually have about 31% dodge, so I have a much higher chance to dodge an attack than parry it, meaning that my stacks don't all get wiped constantly like a warrior or paladin who have much closer dodge and parry numbers. Usually about the time I start getting to 24% parry, (meaning I am now at over 64% total avoidance) is when the stacks will either fade and start over, or the proc will hit.
My other benefit comes in the form of my pocket healer, a resto druid, who has that lovely talent on Wild Growth that gives me free RP. Can anyone say RS and FS out the ass?
So there you go. its late and im tired. bask in the glory that is the blade ward enchant, just make sure you have a crapton of EXPT
In closing I will add. With most cases it may be true, but Blade ward is a viable and better option than 2% parry per sword. 200 parry rating is ~3%, stacking up to a total of 5 stacks, and usually hovering around 3-4 stacks, meaning it is going well above 4% parry, even on 2 stacks it does. And it procs a hell of a lot.
Sorry, we're still not convinced that it should be scored 15. We did some extended research on the subject and yes, I gotta admit it was buffed recently and it is better than it used to be. However (for dual wield), Rune of Swordbreaking gives 2% parry always, while Blade Ward gives parry rating which is subject to diminishing returns (and it depends on proc). I admit that Blade ward should be worth more, it's just that almost no one would put some very expensive enchant when he/she can get a (arguably) better free enchant through Runeforging
And the enchant isn't really expensive anymore. Abyss crystals can be farmed in normal ToC. A Titansteel Bar is easy enough to come by for relatively cheap. (Probably easier since most DK's are either Mine/BS or Mine/JC) And 8 Greater Cosmic Essence is gonna depend if you have a single enchanter friend who might cut you a good deal. All in all, no I would not suggest this enchant for anyone wanting to be a DW DK. I put this on 2 Legacies of Thunder and 2 Titanguards, high end, high quality tanking weapons. So I think it is worth it considering I 3 stack without any effort lol.