Stuff like blade shapes and features are hard to patent because there have been so many different knives made that finding an old one withsay a talon hole is easy.
I know alot of cutting competion knives have them for a safer style of lanyard.
Loveless chute knives had them but with one at the top as well. Cold Steal took alot of heat for the wave feature their AK47 folder had.

I think the reason not to do something like that is 1 to show respect and 2 to do
something different that you can say is your own. If Dan wanted to make Busse knives he could but he started his own company to do something different.