W-Obsidian Ingot is currently the hardest obtainable ingot in NetherCraft. with W-Obsidian Ingot you can make W-Obsidian armor that is about as strong as diamond.
Unfortunately, there are no tools that can be made from W-Obsidian Ingots. W-Obsidian Ingots can be made by combining some W Dust and a Neridium (not iron) bucket of lava. The Neridium Bucket will be given back to you after crafting, but it will be empty.
Ghasts are trapped in the Nether forever, fated to guard and protect its powers from Surface visitors. Ghasts occasionally mourn because of this, and cry. They cry a special type of liquid, known simply as Ghast Tears in their liquid form, and W Dust, in it's solid form. W Dust simply stands for "Water Dust," and is formed by the combination of Netherrack blood, Ghast Tears, and heat, and has properties very similar to water, since it can easily cool anything, especially lava, forming obsidian ingots. This Netherrack containing the dried product of this combination is often extremely dense and strong, and can only be mined with Pyridium and Linium, the two strongest materials found in the Nether. The W-Obsidian ingots, as they are called, are often used as very strong and durable armors, but are also used to recreate portals back to the Surface world.