The Gurubashi Arena drops a chest every three hours. In this chest one will find various loot as well as an Arena Master trinket. The trinket starts a quest to collect 12 of the same trinkets from the chest. Once one has collected 12 of them they may be turned in for the Arena Grand Master trinket.
Currently the Arena Master is unavailable once one has started the quest. If one does not start the quest the Arena Master trinkets are still able to be picked up. This is a somewhat common bug on vanilla servers.
The Arena Master should be lootable whether or not one has started the quest. Once one has collected 12 of them they should be able to turn them in for the Arena Grand Master trinket.
Steps to reproduce the problem:
Go to Gurubashi Arena and loot the chest including the Arena Master trinket.
The Gurubashi Arena drops a chest every three hours. In this chest one will find various loot as well as an Arena Master trinket. The trinket starts a quest to collect 12 of the same trinkets from the chest. Once one has collected 12 of them they may be turned in for the Arena Grand Master trinket.
Currently the Arena Master is unavailable once one has started the quest. If one does not start the quest the Arena Master trinkets are still able to be picked up. This is a somewhat common bug on vanilla servers.
The Arena Master should be lootable whether or not one has started the quest. Once one has collected 12 of them they should be able to turn them in for the Arena Grand Master trinket.
Steps to reproduce the problem:
Source: