Why have I been returned? I am sure many of you wonder this question as you glare your narrowed eyes in my direction. Mandos deemed me able to return to Arda, not to return to solitude nor take my newly returned wife away from her family, though I do intend to do anyway. But to assist in this prophecy business. Oh yes, even I have heard of it. It was I who made the great blade that is said to destroy Melkor, and although I wish it back from that mortal, I am only to ensure none take it from him. A pointless task you might say? Hardly. The other reason for my return is the other mortal who is mentioned, Beren. For he, I am to create another blade, since the second was lost and it is to be not as powerful as my prized one, but one able to withstand Morgoth. As if I hardly had room for charity, why should I give my creations to mortals? One word, or Vala actually: Namo. So, after being threatened with threats not to be named here, I was returned to Arda, and I will reluctantly serve my purpose.
A/N: Alright, here's my crazy explanation: The grand-o prophecy.
For those who don't know, the prophecy for the 'end of the world', so to speak, is as follows: Morgoth will destroy the sun and the moon, thus breaking the Door of Night. Eärendil will return with Tulkas, Eönwë, Túrin, and Beren on the plains of Valinor and all the free peoples of Middle Earth will participate in the great battle known as Dagor Dagorath, or the Battle of Battles. Tulkas will wrestle with Morgoth, but it will be by Túrin's hand that Morgoth will die; his black sword Gurthang will pierce his heart. The sword, as often forgotten, was forged by Eöl.
{A smaller part of the prophecy is that Beren will return with the second dark blade (remember Eöl forged two) and assist with the fall of Morgoth. But since the second blade was lost, while the other landed in the hands of Turin, Eol has been returned to forge a new blade for the hand of Beren.}
Then the Pelóri Mountains will be leveled, the three Silmarils will be recovered from the Earth, sea, and sky, and Fëanor's spirit shall be released from the halls of Mandos to give them to Yavanna, who will break them and rekindle the light of the Two Trees.
Ta da~