Whilst diving off the Thandol Span in Wetlands (or Arathi Highlands, depending on the end you're thinking of), you discover a skeleton amidst the wreckage of the western span. The dead soldier had been trapped by falling rubble, and unable to deliver the letter you find in its hand.
War has more than enough misery to go around, and has taken its toll from the king as well. While he cannot bring Sara's husband back from the Twisting Nether, he can pay tribute to him.
The king intends to commission a statue to Sully, and asks that you oversee the project, sending you to the sculptor Grand Mason Marblesten.
You go to Darrow Hill, and finally discover a cave that has pieces both suitable for the statue and small enough to carry away with you. You gather the amount that Marblesten asked for, though you have to fight off the many Yetis that inhabit the cave in the process.
You deliver the stone, and watch a master at his craft.
Some time passes, and Marbelsten completes the statue. While he arranges for the statue to be delivered and erected, he asks you to take word back to the king.
The king is quite pleased with the outcome: a monument to the Sully, and all the fallen of this war.