Some of this anatomical discussion is getting a little far afield from the basic topic: Emerson made 5 Sentry Removal Tools (SRTs) on a trial basis. Each had a cqc8-like handle with a very curved, chisel ground blade that was sharpened on the top and bottom of the curved blade, which tapered to a fine point. Two of the five had serrations added to the top, making them even more effective, and at least two had Black-ti coating. An interesting side feature was he drilled a small hole through the handle near the tip end, into which you could insert a paperclip. Its purpose was to be used as a safety so the blade couldn't open, even partially, during tactical events like parachuting, since the double edged blade was a danger on both sides.
According to Ernie, he gave out a couple for field testing, at least one of which came back in rough shape. They were determined to be too limited in scope to be fielded as a regular issue item by the SEALs, so he never made any more. As to their use, picture the blade with a crescent of very sharp edge facing upward when the knife was held in the fencer position. If the wrist was rotated ninety degrees, you have the pointed,curved blade ready to slice as you pull it towards your body. That, in essence, was the technique they taught at Coronado in the seventies, anyway.