This limited edition folder like others Spyderco produced is using a new steel designed by Hitachi. ZDP189 is a laminated steel where the inner core of the blade is much harder than the outer shell surrounding the harder steel. This is very similar to the Japanese swords and combines both strength and extreme edge keeping due to the hardness of the cutting edge. Unfortunately it can be challenging for some to sharpen a blade when its 64 or 65 Rockwell hardness. As a result there are many that don't care for the steel since trying to sharpen it back up to snuff gives them so much grief. If you have the right tool for the job though this steel is probably about as good as man has created for edge keeping.
Lignum is one of my favorite woods. I often times grab a piece of scrap in my shop just to sand it for a few seconds because I love the smell of this wood when you work it. Lignum has a long history of being used for knife and utensil handles. Its still used in the marine industry for boat engine drive shafts, and for sheaves and other parts in the building of sailboats, and even sees a lot of use for judges gavels to this day. Its the heaviest, densest, strongest wood on planet earth according to what I've read. Unfortunately though its hard to determine when you have actually been sold Lignum and when you were sold Vera wood, a close relative. This is quite common. I have some of both woods myself. Both work and even smell very close to the same and in fact there is a lot of evidence that Lignum Vitae is not really just referring to one species of tree but refers to a family of them. True lignum for the tools mentioned above though is denser and heavier than these others and sinks like a rock in water and once you see and handle both you can tell which is which. Still though I've used both and like them fine.