I see many of the nice and great knives that your showing will have a leather or cord thong. Some with a bead tied thru a hole in the handle. Why? In my mind I see something to trap blood,fat and goo. This is why I gave up on my folding hunting knives. Standing at the sink scrubbing deer fat out of the inside of a folder is not the way I want to spend my time in deer camp.....
I asked a similar question several years ago. The answer(s) I received is the lanyard is to be attached to your wrist so you don't drop/loose your knife while working. My working knives always have the lanyard removed.
The lanyard can also be used to pull the knife from the sheath.
10/4
If you use cheap shoe laces or paracord and tie a couple knots it sure makes it easier to pull it out of a tight sheath
Then if you get it nasty,
just cut it off and dispose of it and tie on a new piece.
If you lay it down and forget about it and have to come back for it, a bright colored lanyard can sure help.
If the lanyard has value,
Just take a fingernail brush, soap and water and voila'
ya!
GWB