Step 3 - Obtain 25 Hadium Flakes and 10 Motes of Light Step 2 - Speak to Lord Shaxx, The Crucible guy She will give you the quest 'A Broken Will'. Step 1 - Head to the Tower and talk to Eris.
To obtain this quest, you need to complete the main 'The Taken King' quest line and unlock Patrol mode for the Dreadnaught. The name of the quest is 'A Sword Reforging'