Master's weapons used to be the PvP reward but got moved to dragonstar a long time ago.
I don't think weapons like that should be buyable with AP though as at the moment AP is far too easy to farm (most people can make around 1 million a week by barely playing and just mindlessly following the zerg). If anything it should be linked to campaign rewards in some way (masters weapons would drop for being in the top 2% at the end of a campaign if I remember correctly).
Again though I think masters weapons already fill the special PVP gear slot and vDSA is one of the easiest pieces of content to run in the game so I'm sure most people don't mind farming it. (I farmed it for months to get my defending bow and then for months after it to get 3 guildies the bow as well).
i disagree , i don't think we should keep rewarding the people that are already at top tier,
it should be available to every 1 who play the game and not those who reach top 2 or 10 %.