honestly, Luthien and her descendants don't own the Silmaril because she fought for it or because of weregild or whatever. the weregild situation in the Luthien drama is the weapons of Curufin that Beren takes from him; that's the payment, the weregild, the gold you pay for a wrongdoing. it's Angrist and Curufin's other weapons. not the Silmaril. you need to understand that Tolkien says super explicitly that the Silmaril ownership system is morality (and therefore religiously) based. he declares super clearly, black on white, that the sons of Feanor had right to the Silmarils before that right is forfeited because of their deeds, that presumably meaning Alqualonde's theft of ships and ensuing fight already. that right is forfeited, not as payment, but inherently, metaphysically, which Tolkien also reinforces by having the Valar, authority of Eru in the embodied world, bless them so that only clean hands can touch them. but mind you, what clean and moral hands means is completely arbitrary. the dwarves don't burn for killing Thingol, Beren doesn't burn for killing the dwarves. am I meant to read, say, the dwarves' overreaction to an insult as justified killing, then? as moral? it's okay if they kill someone because he's not giving them what is theirs? it's not possible to construe this narrative unless we understand that its fate is simply not a force of balanced moral judgement, but a force with a specific aim, and it's not possible to make of the story an even field because of it. fate is such that Beren can cross through the girdle; Melian cannot keep him out. in short, the Silmaril's ownership is not a consistent external logic, it's an internal morality that hinges on religious exceptionalism and fatal, near-authorial say-so. remember that Glorfindel is reembodied early explicitly because he aided the divine plan in saving little Earendil: religious favoritism and authorial say-so are a thing (they're the same thing. this is a story, nothing exists that the author doesn't decide. that the in-story divine plan corresponds with the story the author wants to tell and therefore pushes forward with the deus ex machina, that makes it ultimately nothing but Tolkien's say-so). remember also, however, that the final fate Tolkien envisions for the Silmarils is the liberation of their light to remake the world. the imbuing of their beauty for everyone to share. and whatever my opinions on that, it's miles better and a much more apt fate than whatever hoax a rigged religion-based sort of moral ownership represents.
