What exactly does it mean? What weapons are in donor tiers? Do they have special abilities so you don't lose them? I have a torch thing that's a donor tier. Also, what donor ranks have donor tier weapons?
There isn't an actual thing as a 'donor tier' When GTA first came out, there were multiple weapons, (torches, jumpers, etc..) that were in donor kits, mainly jumpers. They were short-lived, being removed rather quickly after the release. Tried talking with Cypriot about adding them back, he said he'd talk with Crew (<-- Crew removed them), guess nothing happened.
This pretty much answers where they came from. They are referred to as "donor weapons". You do not lose them upon death unless you combat log. They are way more expensive than the typical guns you'll see in chests and in the gun shop. Not only more expensive, but more powerful. ^ these are all the donor weapons. Closing as the question has been answered. You can let me know if you have anymore questions.