The design was originally a custom piece made/created by Jason Breeden (and now a collab with Spyderco). I emailed Jason asking this same question so we could pull together a press release. The blade shape was designed to suit him personally and what he wanted for outdoor use. Excuse the cut and paste portion of the press release but this might answer a bit:
"All eyes were on knife designer Jason Breeden’s knives at a recent knife show; hypnotically drawn to a folder with a blade shape unlike anything knife enthusiasts has previously seen. The lower half of the blade was curved like a Hawkbill blade but its tip was bulb-like, perched on top the curved portion like a head on a neck. When someone asked the designer about it, he replied, “My designs are born from need I have experienced. I live in the Appalachian Mountains and am regularly outdoors or in water. A recurve blade has cutting advantages in water but I also wanted a strong tip for outdoor applications.” A Spyderco Round Hole was added and the Spyderco/Jason Breeden Captain came to be. The blade’s unusual shape in effect creates two opposing cutting angles one curving inward, one out. The inward curve holds onto what is being cut keeping it in contact with the sharp edge, ideal for downward and pulling cuts such as rope and line. The outward curved cutting edge bulges out at the blade’s tip for close in controlled cutting like skinning, whittling and horizontal slicing moving the wrist."
Happy Monday to y'all!
Joyce @ Spyderco