As I understand it, Spyderco's patent was for a depression in the blade of a folding knife that allowed the thumb to open the blade. The patent neither specified or precluded the depression going all the way through, nor did it limit the depression to one specific shape. Spyderco's trademark, on the other hand, is for a single specific implementation of a depression as an opening device covered by that patent, the round hole opening device. Except for a single model they have used the round hole opening device, to the exclusion of all other implementations of the patent since they began producing knives. That sole exception was the C27 Jess Horn. It used a pair of trapezoidal depressions in the blade that fit the specification of the patent just as well as the round hole opener does.
Aside from the C27 Jess Horn, the round hole opening device has been used as the opening device on every FOLDING knife that has been marketed under the Spyderco label from their first, the C01 Worker to their latest the C113 Caly 3. The sole exception was the C27 Jess Horn. Since fixed blade knives would not benefit from a round hole opener, or any other opener for that matter, the round hole opener has never been used by Spyderco on them. The presence of holes drilled for purely cosmetic reasons on the SPOT and SWICK do not alter that.
A manufacturer's use of a trademark on one distinct group of products (in this instance folding knives) and their non-use of it on other distinct product groups (fixed blade knives, kitchen sharps) does not impact the legitimacy of the trademark.
Companies are allowed to have more than one trademark, so the existence of other Spyderco trademarks, such as the "bug", does not does not impact the legitimacy of the round hole opener as a trademark.
"Functional" features CAN be given trademark protection, as long as the functionality does not confer a functional advantage. As an example, paint on a vehicle serves a functional purpose, but John Deere has a trademark on a specific color of green.
Manufacturers, including Benchmade, who have used oval and other shaped holes as opening devices have asserted, and continue to assert, in their advertising that the shape of their hole makes it superior to the round hole as an opening device. By that assertion, they have eliminated the argument that the round hole has a functional advantage over other shaped holes when used as an opening device. The fact that ANY hole opener of reasonable size, regardless of shape, has a functional advantage over thumb studs, disks, nail nicks, etc. is beside the point.
The fact that other manufacturers and some custom makers use one or more non-functional round holes as their trademark has no bearing. Nor does the presence of round holes in wheels, donuts, and bowling balls. The trademark in question covers a round hole used as an opening device on a folding knife.
The fact that Spyderco has licensed their trademark round hole to some custom makers and one other manufacturer for use, with attribution, on products that do not directly compete with Spyderco's own wares due to their price-points does not diminish it's validity as a trademark. It is no different than when Jeep and other automobile manufacturers license the use of their marques to companies that make battery powered ride on cars for kids.
Theft is theft, whether the item stolen is tangible or intellectual property. All the rationalization in the world will not change that.
And, for the sake of anyone still unaware of it, I am not now nor have I ever been an employee of, or spokesperson for, Spyderco. My opinions, as expressed here and elsewhere, are mine, and mine alone. The strength of my feelings regarding this matter are a combination of two things. The first is my deep respect for the integerity of Spyderco, Sal Glesser, and everyone else in the Spyderco organization I have had the pleasure of dealing with. The second is, perhaps more self-serving. I make my living, in effect, by selling the fruits of my imagination to my employer, so I take IP theft of any kind, from anybody, very seriously.
Does that sound rediculous? In this thread I can't see how. 
