First teleport from Eirulan to the Azunite Desert. Head east into and through the outpost compound. Continue east down the hill and through the gate. Follow the path a short way west, then go north down the hill and through the camp. Continue north through the gate posts and up the stone steps, dispatching any sand reapers, which come down to greet your party (although they may wait until your party has made it to the top). There's a square tower at the top of the stairs to the west. Enter it and activate the lever to ride the elevator down below. Once down, talk to Master Thestrin and agree to locate his family crypt and retrieve the priceless heirloom to activate the quest.

Return to the Desert Outpost and pass by Soldier Gorath, while exiting via the outpost compound south gate, and then head southeast down the hill and continue on until a large irregularly shaped column comes into view. Skirt it to the southeast, unitl they reach the entrance path. Then follow it east up the hill to the crypt entrance, then open the door and head on down the stairs into A Ruined Crypt.

Head through the door and continue straight ahead until your party reaches the Statue Guardian. Note that there are four side chambers in this area, each containing some Undead Azunite Soldiers and or Archers, a mage or two, plus a War Pedestal. All four doors will be opened once the riddle has been answered and the Heirloom Sword acquired. It's easier to open each door individually and deal with the inhabitants within before solving the riddle, rather than having to take on the contents of all four rooms at once after doing so.

Left click on the statue to be asked the riddle, shown above, which Master Thestrin mentioned (and is noted in your journal). Answer Azunar was first, Xeria was second, Elandir was third, and Zaramoth was fourth to correctly solve the riddle.

The door behind it opens to reveal the Heirloom Sword on a platform and an ornate treasure chest behind it plus two side treasure chests, which should be looted first. Hassat Hunter advises that your character should first answer the riddle incorrectly a couple of times, as each time it's done so, the spawned mini-boss will drop some nice treasure. Pick up the sword and deal with the enemy or enemies, which may erupt (e.g. an Undead Azunite Archer Hero) from one or more locations, if you haven't previously dealt with them.

Once back out on the Azunite Desert, head west down the hill to the end of the dry riverbed, then turn northwest at the base of the small hill and head northwest, skirting the large irregular column just to the northwest. Continue northwesternly up the hill and return to the desert outpost. Once there, return to the square building up on top of the hill opposite the desert outpost to the north and pay Master Thestrin another visit. He notes that they have brought the sword and teaches your party the Magrum Erupto (looslely translated as nasty eruption) chant, which you will not want to recite.

After you hand over the sword he asks your party to not mention this transaction to anyone in Aman'lu, particularly not the elf Athelas, and then teaches your group the more useful Requo Amicum Es chant and he then disappears, completing the quest. However once you encounter the named individual in Aman'lu (in the rear of the Inn on the first floor), be sure to mention it as Master Thestrin wasn't quite what he may have seemed to be, and doing so will enable you to initiate part two of this quest.