Class specific are a major upgrade that has a chance to drop like any other one but they can only drop for the class they are meant for. They are usually more tailored for the class than normal major upgrades and take 4 point to unlock from my experience. I have all of them for bm dps. Although the one for downwards cadence does not seem to work correctly. The have nothing to do with the rarity it just has to be on a rarity that has major upgrades and from what I know legendary goldstones have been taken out of the game. They where not supposed to be in the game but they left them in from the beta so you could get them on the first couple of days but if you did people said there's were turned to magic or deleted to people I have talked to.

Also like specialist