Well my thoughts are all over the place.
First off, fantastic filking job; I'm mentally singing it to the Tolkien Ensemble version. ^_^
Stanzas two and three make me think Beren (specifically Beren in the Nightshade, and Beren sometime towards the end, possibly even after his death). But stanza 4 doesn't work with that.
Stanza 4 does give me a Merry vibe, specifically the way he invokes Bilbo's tale at the Black Gate - "the eagles are coming!". Equally, the whole thing has a
kind of Bilbo feel, especially the line about friends, which works well for the Battle of Five Armies.
The vessels sailing is an interesting one. "Build, save, and depart" - the only context I can put that in is the founding of Numenor, where I believe it was Elvish ships that carried the Men over there, and then left. That would probably point at Elrond, but I can't fit him to the rest.
The other feel I have for the fourth stanza and the last couplet makes that line refer to ships out of Balar coming to the Havens, and puts us somewhere around Earendil. I can make
bits of the rest tie into that, but "turn back" and "return" strongly argue against a Fall of Gondolin setting.
Like I said - absolutely all over the place.
hS