I do some quite similar mountains on 3.3.5a :
Since Blizzard can use extendible textures and 6 textures per chunk on Legion, it'll obviously look better for them, but the idea is easy to understand :
First of all you have to use mostly north/south and east/weast angles because of WoW triangular restriction : other angles will likely look triangular and weird.
You have to flatten some parts of your mountains and make the top have an angle that you keep. (Like 50° toward north, etc) Once the shape is done, you have to texture it, first divising your mountain into blocks with a texture darker than your rock, it's here to create contrast.
Then you have to create a diversity inside these mountains blocks : the top of the block is lighter and the low part darker. You can make this effect with two rock textures, or only one by making a transition thanks to the dirt texture. If you're using an old WoW version, I recommand using the first one only for very large mountains. (The bigger a mountain is, the weirder it looks when you're close)
Try taking all that into consideration, then send us some screenshots, that will help us know what you're missing.
