Jim, Hilary, Cameron, Joe, John, Nick, Glenn, Trevor and Mark,
Thanks everyone. I made a few changes. The only big one is in response to Joe letting me know I'd misunderstood the word "ravelling".
Jim,
Not sure I can manage not changing anything, but that doesn't mean I won't change it back

Thanks for spotting the typo.
Hilary,
I'm glad this ending up working better for you on rereading. I'm not sure there's any real difference in meaning between "awakened by" and "awoken by" in this context. Googling, I see that "awoken" more common in British English, so maybe that's why it stuck out for you? Incandescence isn’t necessarily bright or shining -- it could be a dull red glow, for example. That said, I do see what you mean. I think "shining" is there in part because I like the sounds and because, I think, "shining" adds other associations/connotations (something like a beacon, maybe?). I may still lose it, though.
Cameron,
Thank you. That's very good to hear.
Joe,
About "ravelling", that is annoying! I'd just assumed it was the opposite of "unravelling". I guess “ravelling” kind of works, if I think about an untangling of themes, a drawing out. But as you say it seems opposed to gathering together. I’ve tried something different, and maybe a little overdone. I guess I could just replace "a ravelling of themes", with "a drawing out of themes". I'm now preferring "threads" to "themes", because "threads" connects with "filaments" which are threadlike -- though maybe that's being a bit too clever?
I'm also unsure about "specialised". But if the lightbulb is taken as a metaphor, I don't know that "designer" works well with that, with its connotations of fashion. I wonder if "special glass" is better.
John,
Thanks, very pleased this worked for you.
Nick,
Poe's most famous poem is called
The Raven, in which the N is mourning a lost love; it features a raven that taps at his window and a refrain in which the raven says "Nevermore". Prometheus stole fire from Olympus and gave it to humans, and his punishment was to have his liver pecked out and eaten by an eagle every day, whereupon it would grow back in time for this to be repeated the next day.
Useful to know that you find the "slid in beneath" construction awkward. It does seem natural to me: it slides into the space/flesh beneath the fingernail. Can you say more about what bothers you about the Poe sentence? Is it a rhymical issue? The poem does become increasingly iambic as it progresses, but this sentence is flat prose. I'd wanted the opening to sound more like reportage, but it might be possible to smooth it out.
Glenn,
Thanks for your reading of this, and for letting me you found it moving.
Trevor,
Thanks, it's always interesting to consider different ways to order a poem. I do need the Poe part, I think, if only to set up the black feathers. I think "Filaments", plural, works better than the singular, because a filament is a thread of sorts, and there are various threads in the poem.
I'd also wondered about "bedroom" and have taken it out.
Mark,
Thanks, that's very pleasing to read. Good to see you back here.
Thanks again everyone,
- Matt