I've carried the same simple 2-blade knife in a small black sheath on my belt for almost 20 years. I use it most often for opening letters and boxes.
I think I've been asked to take it off once (other than airports). In 1988 I forgot I had it on my belt as I went through security at the Zurich airport in Switzerland. They actually let me keep it - that would never happen today.
I have at least 12 hunting knives but the two that are always with me (either in my pack or on my belt are the Puma Skinner and the Puma Lord
When I'm in the field working I now carry a Leatherman Wave.
And don't even get me started on my hand made knife collection and the three original Indian knifes I have from the 1810-1830's.
Not much for fighting knives - I've known enough special forces guys that would just take it from you and kill you with your own knife - they taught me to never bring a knife to a gun fight.