Netherweave Bracers recipe - Frostmourne

Hello,

I have been trying to find the recipe for Netherweave Bracers for the last 2 days. I leveled tailoring many times and I know this recipe is sold by the vendor in Hellfire (Honor Hold). Unfortunately, I was unable to get my hands on the recipe. I camped the vendor for an entire day with no luck. Then I went to Shattrath to check with all other vendors/trainers and still no luck. This recipe cannot be sold on AH as far as I know, and its not on AH as I have checked, still no luck!

What is happening ?