I've learned a couple warping lessons. One, it seems like on my 1080 blades that those with an edge quench or clay quench want to warp more often. A full hard blade is less likely to warp in my experience. Two, don't lay a blade down on one side after the quench. Either stand it up on the spine, or put it on a wire rack. If you take a fresh quenched blade and lay it on your anvil, etc., it will warp. Three, normalize multiple times prior to heat treat if the blade is forged. As far as this particular blade, it was a 6 inch hunter of 1/8 D2, and I put it in the foil packet along with a small 3.5" keychain knife, also of 1/8 D2. After the soak, I pulled the packet out and put it on my wire rack to air quench. My suspicion is that the small blade held some heat that made the larger blade cool unevenly. Uneven martensite formation is what causes the warping. That's also why they say don't agitate in the quench side to side, only tip to butt or edge to spine. If you're stirring sideways, one side of the blade will cool faster, and you'll warp. There may be other reasons and cures for warping, but I can verify that what I've said in this post is true in my experience, may not be universal, but is not just some jibberish I learned on the internet.