Ëarendil and Ancalagon

[Formendacil]

Originally Posted by Andsigil

This is one of the most disappointing scenes in all of Tolkien's writing for me. Here had a chance to write about a terrific smash-up, and he reduced it to: Ëarendil shows up, Ëarendil glows, Ancalagon dies. I wish Tolkien had been more descriptive in this passage like he was about the battle between Fingolfin and Morgoth.

To be fair, that entire chapter in the published Silmarillion is basically bald reconstruction from old outlines and the like on Christopher Tolkien's part. Tolkien fails to give us an indepth account of that at any point in his life... which, as you note, is a great disappointment.

Given that Eärendil bore a Silmaril, if I had to speculate, the obvious answer would seem to be that the Jem of Fëanor probably played a role--and the "white light" might be connected thereto. Exactly how Eärendil used the Silmaril is another question--but we do know that the touch of the Holy Jewels is painful to evil. As the greatest of all dragons, with the cognomen of "the Black", it seems reasonable to speculate that Ancalagon might have found the touch of the Silmaril especially painful.