Sailor Moon's magic crystal was known as the Silver Crystal, and her knigdom was known as the Silver Millenium. Mamoru's magic crystal was known as the Golden Crystal. Both of these are in keeping with the associations given in the description, since Sailor Moon was the incarnation of an all-powerful goddess, and Mamoru was a king (and also somewhat useless when his powers were compared to hers).
There was an old Spider-Man villain-turned-somewhat hero called Molten Man who was colored gold but was not a nice guy. When he reformed, instead of turning into a full-fledged superhero as most Heel-Face Turn cases do, he mostly tried to lead a normal life after he gave up villainy.
The Silver Surfer is a cosmic herald, who can fly through space and draw on raw cosmic force to blast his enemies.
The T-1000 from Terminator 2 very much resembles mercury, and its shapeshifting properties are definitely thematic.
In the Arcia Chronicles, the Praetorian Guard of Tayana are split into the king's personal unit and the crown prince's unit. The former are associated with gold and mainly deployed to parades and celebrations. The latter are associated with silver and regularly carry out force recon and special operations.
Both the "fanciness" and the "royalty" symbolism of gold are invoked by Moist Van Lipwig after picking up a golden suit in Going Postal to go with his golden postal worker's hat (in the next book to star him, he covers a top hat in gold glitter for the same effect on being put in charge of the bank). As a former Con Artist, standing out is pretty much how he succeeds. Made a plot point when it turns out an army of ancient golems will listen to him, because the gold suit is similar to what their handlers would have worn.
In A Song of Ice and Fire, the former blacksmith to the Baratheon family compares each of the 3 Baratheon brothers to different types of metal. Youngest brother Renly is copper, pretty and looks nice, but not worth much in a medieval society. Lawful Stupid middle brother Stannis is like iron; hard, inflexible, but brittle too. He'll break before he bends. Oldest brother Robert was the one that the blacksmith considered true steel, but 15 years trapped in a loveless marriage doing a job he hated ruined Robert's "true steel".
In The Lord of the Rings, the EntTreebeard says at one point that the wizard Saruman "has a mind of wheels and metal". This implies a cold, intellectual, sterile view of the world that has no place in it for the love of anything organic or growing. Considering the Green Aesops of LOTR, this is not a good thing to be in that series, and Saruman is dominated by Pride, Resentment and Jealousy, all of which cause his downfall.
Prince Nigel Haldane, Duke of Carthmoor in the Deryni novels is nicknamed "the Iron Duke". He's proven himself at combat from the age of twenty onwards, and he has Gray Eyes to boot.
The Steel General in Creatures of Light and Darkness is an ancient warrior from Old Earth who fights for the downtrodden, the underdog, and the rebel. As he's been wounded in battle, he's had parts replaced with steel, till all that remains of his original body is a ring of flesh he wears on his pinky.
The various Oz books had a handful of metal-themed characters. The best known is Nick Chopper, the Tin Man, however there was also Tik-Tok the mechanical copper man, and an iron man who guarded the Nome King's palace.
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Sapphire And Steel: Steel, Lead, and Silver all have symbolic connections to the metals they're named for.
The origin of Led Zeppelin's name. To quote TOW: "One account of how the new band's name was chosen held that Moon and Entwistle had suggested that the supergroup with Page and Beck would go down like a "lead balloon", a British idiom for disastrous results. The group dropped the 'a' in lead at the suggestion of their manager, Peter Grant, so that those unfamiliar with the phrase would not pronounce it "leed". The word "balloon" was transformed into "zeppelin", perhaps an exaggeration of the humour, and to Page the name conjured the perfect combination of heavy and light, combustibility and grace."
Field Marshal Arthur Wellesley, 1st Duke of Wellington was nicknamed "the Iron Duke" for "his consistent political resolve" (as The Other Wiki says).
Prince Otto Von Bismarck was known as "the Iron Chancellor", in part for his diplomacy of realpolitik and his powerful rule and in part for a famous speech he gave advocating strong military power in a unified Germany.
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.