The Civilian was developed to cause maximum damage with minimal skill. Sal created the Reverse "S" blade shape to replicate the mechanical function of an animal's claw--piercing with the tip and drawing the material to be cut into the concave of the hawkbill section. One disadvantage of hawkbills when cutting limbs is that they can hook on bone, stopping the action of the blade. The "belly" near the heel of a Reverse "S" cuts aggressively, but also "fills" the base of the edge's concave curve. If you make contact and start the cut there, it pushes bones away and feeds the material into the hawkbill section.
During my service with Spyderco, I've had the honor of meeting two people who used the Civilian for "serious" purposes. One was a law enforcement officer who was ambushed by a suspect who tried to take his gun. The officer, to his great credit, had trained for that contingency, maintained control over his gun while drawing his Civilian and killing his assailant with it. The other was a U.S. Army soldier who used it in the context of providing critical medical care for a fellow soldier wounded by an IED in Iraq. Both men assured me that the cutting power of the fully serrated Reverse "S" blade is incredible.
Although designed to be effective with gross motor skills, James Keating took the design and maximized its potential through his in-depth knowledge and skill. His video on the Civilian was actually one of the first to show karambit-inspired technique, long before karambits became fidget spinners for knife guys. James is brilliant and his depth of knowledge on the esoteric aspects of the martial arts is unparalleled.
Back in the day, COMTECH sold Civilian trainers made from exotic wood that were hand crafted by Rob Langford--a COMTECH instructor and one of Jim's primary training/demonstration partners in his early videos. The plastic trainers were molded from resin in rubber molds. The molds were often created by taking real knives, building up the edge thicknesses with clay, and then coating them with silicone. This was done by Edge Molding Company, a partner business of James and COMTECH. Sadly, EMC betrayed James and disappeared.
If you're looking for a bit more history on the Civilian, Matriarch, and their variations, here's a link to an article I wrote for Small Arms Review magazine: http://www.smallarmsreview.com/display. ... icles=3091
I hope this helps.