Shade of Farelaith tells you,

"You... Yes, you could help me, mortal. I need you to slay my younger brothers, who were corrupted into beings of Shadow by our former master, Grael. Please, you must enter this Temple of the Stirring Shadow. The temple has three wings, and one of my brothers serves in each wing. They have lost their names and faces to the Shadow corruption, but they still bear their own weapons... I was a mage in my past life, mortal. Help me, and I shall reward you."

"Enter the South Wing first, and seek out my poor youngest brother, Baranaith. He wielded a spear in life, as he does now in the shadow. Bring me his spear so that I may know his torment is no more."

Several ways to go but it seemed the quickest route was taking the left side and following it back to the exit portal.  NOTE: when Farelaith says seek out *&&^%^& does he mean that, his brother is not uniquely identified nor distinguishable from any other shadow in the dungeon, except for the Spear he drops.  I did find him and his 2 brothers close to the exit portal though.

Shade of Farelaith tells you,

"You have my brother Baranaith's spear? Please, give it to me, so that I know that he has been granted oblivion."

You give Shade of Farelaith Spear of Baranaith.

"Oh, my brother's spear! Baranaith was my youngest brother. He was barely more than a child when we were taken to the slave pits of Haebrous. I failed him, most of all..."

"Take this spear, mortal, as an instrument of vengeance. I have infused it with some portion of my power."

"Now go into the North Wing and seek out my brother Korogaith. You will know him by his axe."

Shade of Farelaith gives you Spear of Winter Flame.

This dungeon I merely wandered ahead straight and eventually killed and looted Korogaith.

You give Shade of Farelaith Axe of Korogaith.

Shade of Farelaith tells you,

"This is indeed the axe of my brother Korogaith. He was just a few years older than Baranaith. He was a hunter and a woodsman without peer. He was the one who tracked down Grael in the wilderness... Oh, would that we had never found that accursed soul again, but perished together in the snow..."

"Take this axe. I have infused it with some portion of my power, to serve as an instrument of vengeance against the dark powers that corrupted my brothers."

"Now go into the East Wing, the last of the wings, and seek out my brother Hiranaith. You will know him by his mace."

Shade of Farelaith gives you Axe of Winter Flame.

The east wing was the shortest dungeon of all, and true to form Hiranaith was close to the exit portal room.

You give Shade of Farelaith Mace of Hiranaith.

Shade of Farelaith tells you,

"Oh, my brother Hiranaith. This is his mace, with which he served in the town guard, before our father was forced to sell us to the imperial slavers. Hiranaith was a year younger than me, but twice as strong. He was my protector in the slave pits. Alas, I could not help him in his time of need..."

"I have infused the mace with some portion of my power. Take it and use it against the shadowy things which corrutped us. I give you also my journal, that you may know something of Grael, who was once our master and twice betrayed his followers."

You've earned 1,500,000 experience.

Shade of Farelaith gives you Mace of Winter Flame.

Shade of Farelaith gives you Farelaith's Untranslated Journal.

Shade of Farelaith says,

"I failed them... I failed them all..."

"You have helped me already, have you not, mortal? I know your kind are quick of thought and short of memory..."

NOTE: depending on your past selection you return to the NPC based on your Royal/Rebel allegiance.

You give Edobar the Esoteric (26.0N 47.0E, Cragstone Library) Farelaith's Untranslated Journal.

Edobar the Esoteric tells you,

 "What a fascinating account. I am immensely grateful you brought this to my attention. It sheds such a great deal of light on the mystery of Grael!"

You've earned 500,000 experience.    Probably level based, xp for lvl 230.

Edobar the Esoteric gives you Our Bitter Winter.

OR

You give Gallatria du Ressetta  (69.9N 62.6W, Sanamar Great Hall) Farelaith's Untranslated Journal.

You've earned 500,000 experience.    Probably level based, xp for lvl 230.

Gallatria du Ressetta tells you,

"You have done well to bring this to me. His Majesty the King will be pleased with the information contained herein, even if it has no immediate applicable value. I will share the translation with you..."

Gallatria du Ressetta gives you Our Bitter Winter.