Rethu's Incessant Courage is a new craft legendary gear in 7.2. Requires lvl101 and can be traded in game. Because the map of the broken coast is very small, so there is the big chance for the fight between alliance and horde. This is a good use for this kind of craft legendary gear.

Rethu's Incessant Courage is made by the Blacksmithing. The recipe can be bought and learned at the professional trainer. It needs Blacksmithing 800. You need prepare 2 legendary items and some blood of Sargeras. Nethershard Essence can be exchanged by Nethershard or bought at an auction house with WoW Gold. But the Hammer of Forgotten Heroes need to do some quests. You can get the quest from the Broken Shore.
In order to start the quest, you'll need to have the Nether Disruptor building active in the Broken Shore. Then you'll be able to talk to Eliezer Hammerbeard to receive Armorcrafter's Commendation. Receiving that item will start The Legend of the Four Hammers, which requires you to go to Dalaran to obtain  Legends of the Four Hammers.
Then you get to listen to a  Fashion History and a Philosophy of Style.
After this will give you 4 new quests:
  Armor of the Ancients :  Requires 100 Ancient Demonsteel, looted off creatures on the Broken Shore.
  The Godfighter : Requires Godfighter Hammer from Odyn in Mythic Halls of Valor.
  The Dragonhunter :  Requires Dragonhunter Hammer from Dargul in Mythic Neltharion's Lair.
  The Hellslayer :  Requires Hellslayer Hammer from Helya in Trial of Valor in any difficulty.
If you have all of these, you can craft Rethu's Incessant Courage You can choose to use by yourself or sell it at AH.
Are you worried about the first legendary gear? Collect WOW gold to buy one at AH, this is also a good choice.