I'm going to write a stream of consciousness review as I read. :)

Firstly, I love the opening song. It fits the story and now I shall never hear this song without thinking of Fingolfin! :)

This sentence:
"Opening his eyes, he once more sought for his son, so like himself – driven by duty and responsibility. He smiled slightly to himself. There were some things Findekáno had inherited from his mother rather than himself: the compassion, the love and the humility that he and his own elder brother both lacked."

I was a bit confused by this sentence; I had to read it a few times. There are lot of pronouns that make it hard for me to follow who the "he" and "him" are. I'd suggest putting proper names in their places, something like:

"Opening his eyes, he once more sought for his son, so like himself – driven by duty and responsibility. Fingolfin smiled slightly to himself. There were some things Findekáno had inherited from his mother rather than his father: the compassion, the love and the humility that Fingolfin and his elder brother both lacked."

Fingon's musings about the world Ereinion will inherit--and Fingolfin's reply--is heartbreaking. So is the way that Fingolfin folds his rings into his son's hand. One can only imagine Fingon's awakening (and you mention this too, later! What a sad moment.)

In the fight scene, the word "dance" is used a lot. It's a great word, but I'd suggest being a little more sparing so that it doesn't become redundant.

But in all, a beautiful and heartbreaking story about a time in the history of the Noldor that receives surprisingly little attention. (I am among the guilty. :) You effectively bring these characters down from their places as epic figures, princes, and kings and show the personal impact that this must have had on the Noldor.

Very powerful. I very much like the characterization of Fingolfin and Fingon in this piece. Extremely plausible scenario of why and how Fingolfin chose to act as he did. I've often asked myself what kind of man would do what Fingon did to rescue Maedhros--a similarly suicidal stunt, but with a purpose that is, despite that, life-affirming. Well, the one answer could be: the kind of man who had a father who would act as Fingolfin did when he called out Morgoth.

I think this is a very vivid retelling of Fingolfin's death.  You were able to convey the dark hopelessness of the Quendi at that hour so well. 

Really glad to find this.  Fingolfin has to be one of the most unfairly underappreciated characters in the Silm (I really want to write something for him but haven't managed it yet).  I've often wondered what was going through his mind at the end and this is a fine take on it.