First off: Is the rank knife applicable only to the one who buys the knife or is it with whoever is the last to pick it up? Secondly: If it is applicable to the one who buys it and someone sees an elite-colored knife, but there is only one elite on the server, is that enough evidence to justify killing them on sight if someone finds the elite knife in a victim?
1st Question: Only the person who buys the knife I believe, I've never tested this though so I could be wrong. 2nd Question: Yes. Edit: Even if my response to the first question is wrong you can still kill for it since if you find an elite knife in a victim it means that an elite is the one who knifed them, and if there is only one elite on the server it's common sense from there.
1st question: The rank knife was part of the christmas holiday event where any rank was able to purchase the knife and then have that as opposed to the regular knife. Since Christmas just passed roughly a week ago, it's why you see so many players with it. And the rank knife is only applicable to those who buy the knife and have it equipped. So if you picked up my rank knife, you would have the admin color (dodger blue) knife. It does not change colors when someone else picks it up, it will be the color of the original person who first purchased it. 2nd question: Yes that would be acceptable reason to kill the player as that would fall under common sense. Since only an elite bought the knife, and there is only one elite on the server (the player you would kill.) Hope this helps!
Since everything has been said I'll just add something to the 1st question: The knife keeps buyer's rank color, BUT Highwon left a bug (intentionally) that allows to reset the color of the knife by simply throwing it. It will lose it's previous tint and will acquire the color of the holder's rank (or it will look like a default one if the new owner has no rank). This way people who dislike one's color can simply throw it and apply their own.