These "Nightmare" swords were designed by Modell Design LLC exclusively for EverythingWingChun.com. They are a very limited collector's edition Butterfly Sword featuring multiple grinds on the cutting edge (that can make it a "nightmare" to grind). The two grinds here are a lenticular/convex grind near the tip side-by-side with a hollow/concave grind over the bulk of the cutting edge. The lenticular grind provides more steel to reinforce the tip for stabbing techniques. The two grinds here are a side-by-side set of hollow/concave cutting edge grinds that are very difficult to do well. These high-quality collectors swords are real weapons and very dangerous.