The Fangs of the Father (Golad, Twilight of Aspects and Tiriosh, Nightmare of Ages) are two legendary daggers, granted as a reward to players who complete the relevant quest line. While the daggers themselves do not have a class restriction, the quest line is only available to Rogues.
A few important notes regarding the daggers:
There is a Main Hand Dagger of 1.8 Speed (Golad, Twilight of Aspects) and an Off Hand Dagger of 1.4 Speed (Tiriosh, Nightmare of Ages).
Each of the two daggers has a red socket with a 10 Agility socket bonus.
The Main Hand Dagger offers Weighted Blades Icon Weighted Blades, an on-equip buff that greatly improves the damage of Sinister Strike and Revealing Strike. This is to make the daggers viable for Combat Rogues, who generally have lower DPS if using Daggers.
The Main Hand Dagger provides you with Embrace of the Destroyer Icon Embrace of the Destroyer, an on-use ability that slows falling speed.
The set bonus of the daggers is a Item - Dragon Soul Legendary Daggers Icon proc that grants a stacking Agility buff (17 Agility per stack), stacking up to 50 times. Once the buff reaches 30 stacks, each attack has a chance to consume the existing stacks and grant the player 5 combo points as well as causing finishing moves to generate 5 combo points, for 6 seconds.
The quest chain for obtaining the Fangs of the Father is comprised of 13 quests. Most of the quests can (and, due to phasing, must) be completed single-handedly by the Rogue. In addition to this, a few quests will require players to venture into the Dragon Soul raid and complete some very basic tasks, with the aid of a raid group. Compared to the two most recent legendary weapons, Shadowmourne Icon Shadowmourne and Dragonwrath, Tarecgosa's Rest, obtaining the Fangs of the Father puts a lot less emphasis on raid content. Players who embark on this quest line will not only obtain a pair of extremely powerful daggers, but will also be privileged to experience a very compelling story-line that touches on the future of the Black Dragonflight. Please note that none of the parts that involve the Dragon Soul raid instance can be completed in LFR. Only the standard 10 and 25-man difficulties (normal and heroic) can be used for this purpose.
The quest chain is comprised of the following quests:
Proving Your Worth;
A Hidden Message;
To Catch a Thief;
Our Man in Gilneas;
The Deed is Done;
Our Man in Karazhan;
Blood of the Betrayer;
Victory in the Depths;
Sharpening Your Fangs;
The following items will be required for the completion of the quest chain:
Cryptomancer's Decoder Ring (quest item obtained by pick-pocketing Hagara the Stormbinder, the 4th boss of the Dragon Soul raid);
10,000 Gold, to be paid to your faction's Ethereal (Thaumaturge Rafir for Alliance and Thaumaturge Altha for Horde);
333 Shadowy Gems (found in containers that drop from bosses within the Dragon Soul raid);
60 Elementium Gem Clusters (drop from bosses within the Dragon Soul raid);
Fragment of Deathwing's Jaw (quest item obtained from killing Deathwing, during the Madness of Deathwing encounter, on either normal or heroic difficulty, in 10 and 25-man).
As you progress through the quest line, you will obtain the following two pairs of daggers before obtaining the legendary ones:
Fear and Vengeance, of item level 397;
The Sleeper and The Dreamer, of item level 406.