Elves and death

[The Might]

Well, because of his noble sacrifice another exception was made at first in his case - he was allowed to return to the Undying Lands, although he had participated in the rebellion.

Why he was then allowed to leave the Undying Lands and got to Middle-earth remains a mystery. I doubt he was the only Elf valiant enough to leave Aman and go help the Elves of M-e, maybe it was his skill that played a part there. After all, it's not like the Valar wanted to allow all the Elves there to leave and go destroy Sauron, they had already done that once and it was enough.

So maybe he was kind of a special agent of Valinor chosen due to his skills, courage and possibly also friendship to Gandalf for example? He may have befriended Olorin during his stay there after all...

Thing is he was among those best qualified to come and support Elrond.