Geode, no problem. This is actually a question that I get asked quite often.
It took over a year of design work to come up with a design that I was happy with. I sat down and asked myself what the knife was (a) meant to do and (b) what it was most likely to actually do. The former being the most important of the two questions at hand. It is fine to build a super tough tank killing folder, but if 99% of users are only opening boxes with it, then there is a problem. Everything is a give and take. Build it super tough and you lose cutting performance and carry comfort. This is due to the fact that it has to be thicker and heavier. Many other trade off issues also come to mind.
These folders were meant to be practical EDCs with a personal defense side. So what does EDC really mean? What do we REALLY do with our pocket knives. Open boxes, open letters, cut rope/twine, open those awfull plastic "blister" packs that everything seems to come in, and handfulls of other light tasks. Rarer but still occuring is wire stripping, strap cutting and a few other tougher but light duty tasks. So with these tasks in mind the knife did not need to be wrecking crew tough. It was not meant to prune plants or to prepare sushi so chisel grinding was out.
I set out to really pay attention to how my favorite knives performed during these cutting chores. I used dozens of differant knives over the coarse of several months (including my all time fav a TTF-1). The one thing I noticed about all the blades I used, is that reguardless of blade shape, the blade and handle were in a straight line. Geometry actually hindered the function of the knife. By having the knife perfectly straight (or nearly straight) it caused the wrist to have to be excessivly bent for most EDC cutting chores. This wrist position (during prolonged cutting sessions) tended to tire the arm and hand rather rapidly. There had to be a better way. So I took my TTF-1 and stared playing with differant "rakes" (handle to blade relationship angles). I would set up a rake and snug up the pivot pin until the blade would not move. I then would go back and perform all the tasks again. I kept doing this until my wrist was in a mostly neutral position during the cutting.
Then came the handle design. This was simple. The hand is not designed to hold straight items. Curves are much more comfortable to hold over prolinged periods. So I blended a curved handle with the raked blade and the Pelamus is what I came up with. It took a bit more fine tuning to get a design that fit the majority of hands but it was mostly tiny mods. The swell on the bottom was added after a long talk with another maker about "control bumps". By adding these little swells you could dramatically increase the amount of control the user had over the knife twisting in his/her hand. The big bonus was that this added feature did not take away from any handle comfort.
After the first design proto was mocked up I found an additional bonus to the raked blade. During personal protection uses a knife with zero rake tends to want to ride up on the the target during slashing strikes, that is unless you flex your wrist at an odd angle. Then the problem arises that since you no longer have a "Locked Joint" you had a better chance of losing control of your cut. With the heavy rake of this design your wrist can stay fully locked and in control while at the same time presenting the blade at an angle which caused it to actually plow into the target. This effect was further inhanced by adding the recurved blade.
I personally found that a much heavier rake works better for me, but the vast majority of the buying public have had a hard time accepting it, so for these it has been toned down enough to make the acceptable but still retain the positives.
So there you have the long and short of it. Hope that long winded response answered your question.
Thanks
Ron
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