What type of English is used in the dialogue of the Lord of the Rings movies? [closed]

Epic prose deals in weighty and significant matters, to do with times and periods that transcend normal life, with the formative doings of extraordinary people. The question of how to learn it I find difficult: how does one learn any linguistic style other than by example? Read, reflect, write, learn from criticism, and try again. I doubt that there is any rule book.

Once on a time
    in comment contrite 
Sir Reginald Dwight
    anon did us write:

It's of a slightly higher register, but actually not by much. Especially not in writing. Anyone in here can, and occasionally does, write like that off-the-cuff. Doesn't need to be an epic tale. Can be a YouTube comment. You can easily learn this "type" of English exactly like you would any other type of English. Through repeated exposure and practice.

The two quoted paragraphs of the dialogue from Jackson’s film are somewhat odd in that they are not all of one cloth woven. The first bit with Elrond’s bitterness put into curt words is purely an invention of the screenwriters alone, while the last bit, the lyrical bit that perhaps seems out of place here, they copied in word for word from Tolkien’s actual writings. But not from his dialogue; from a historical narrative, which serves a different purpose. It wasn’t spoken aloud as it was in the movie.

Those writings are to be found in one of the Appendices to The Lord of the Rings, in Appendix A which contains a portion of “The Tale of Aragorn and Arwen”, whose borrowed line I’ve placed in bold:

‘“Estel, Estel!” she cried, and with that even as he took her hand and kissed it, he fell into sleep. Then a great beauty was revealed in him, so that all who after came there looked on him with wonder; for they saw the grace of his youth, and the valor of his manhood, and the wisdom and majesty of his age were all blended together. And long there he lay, an image of the splendour of the Kings of Men in glory undimmed before the breaking of the world.

‘But Arwen went forth from the House, and the light of her eyes was quenched, and it seemed to her people that she had become cold and grey as nightfall in winter that comes without a star. Then she said farewell to Eldarion, and to her daughters, and to all whom she had loved; and she went out from the city of Minas Tirith and passed away to the land of Lórien, and dwelt there alone under the fading trees until winter came. Galadriel had passed away and Celeborn had also gone, and the land was silent.

‘There at last when the mallorn-leaves were falling, but spring had not yet come, she laid herself to rest upon Cerin Amroth; and there is her green grave, until the world is changed, and all the days of her life are utterly forgotten by the men that come after, and elanor and nimphredil bloom no more east of the Sea.

‘Here ends this tale, as it has come to us from the South; and with the passing of Evenstar no more is said in this book of the days of old.’

As you see, this is written in somewhat ‘elevated’ language. It was not originally dialogue. It fit well within the context where it was originally found. Whether it was seamlessly patched into otherwise pedestrian dialogue for the movie is not for me to say.

There’s a reason for the elevated language. High fantasy is written in Northrop Frye’s high mimetic mode because it consists of stories about heroes, people who are better than ordinary humans. See this essay for how this applies to the heightened language and rhetorical devices of Tolkien and LeGuin. Tom Shippey even convincingly argues that The Lord of the Rings uses all four modes for different places and characters in The Road to Middle-Earth: How JRR Tolkien Created a New Mythology.