My main motivation in writing fractured universes are the weapons mentioned or shown in them. Rather than the plot or characters, its the weapons that makeup the best of the fight. Of course, the characters that use them must also intrigue and gain popularity or a connection from the audience to make the weapon shine even brighter during the clash of mettle. But, what makes a legendary weapon unique or worth anticipating more than the character that wields it? There is balance, but should balance tip towards my bias, how should a weapon be written and make a wonderful entrance to the story?
Hmm... i would start the conceptualization with a weakness. Like a knife that cannot cut through cheese. Then fit that somehow into the universe, give it powers that counerbalance tje weakness to make it legendary, in the aforementioned case a bland 'cut throigh everything else' and go!
I'd say... Anything with its own ability(s). Something that expands the wielder's repertoire. It doesn't have to be overpowering or anything -- it just has to be an important variable that people stress over in fights. "I've never seen that weapon before, what kind of ability does it have..." That kinda thing.
Use an unconventional item! Don't have to an actual weapon! You can draw inspiration from upgrade specialist in another world whereby one of the main weapons the mc uses is a brick that has gone through a couple of upgrades and it's ultimate form is fo it to expand to a few km wide lol...
Space warping whip that breaks a rib of the user everytime it is used. Can be use to create rupture in defense or ripples/distortions in space to attack opponents? I recall a show about a weird room, with everyday items imbued with special and deadly effects. Like a glasses that kills whoever the user is staring while wearing it. Worth the candle even has a sword that eats ones memories to increase attack strength. Gun of friendship, loses a year with every shot fired, but those who get hit by you will like you, variations dependant of victims. Repeated shots for one victim is allowed. Something a human emperor 人皇, heavenly emperor 天帝 uses. A proxy that increases the user's every attributes proportionate to the amount of supporters the user have. Additional benefit is that the supporters also gain some power up too. Drawback is that the user can hear and know every supporter's desires and wishes.
weapon that need price to pay when the user want to use em, like one's blood or soul, or something absurb like one's virginity, lust, karma, wrath, etc..
There are several schools of thought Western 1: it must be extremely big and shiny Western 2: it must be a (somewhat) sentient lunatic Japanese: embellish the hell out of it and make it transform and fly around and shit Chinese: give it a flowery name to strike fear (?) into the hearts of your enemies Korean: strike a dashing pose and present a brief essay-length chuuni speech about how your big shiney somewhat sentient flowery transforming sword will....
Give the weapons history and lore. Say the weapon used to be wielded by a legendary figure to do something historically significant. Make a setting that convey how significant weapons are in the world. Like, say, the top figures of the world's story would change their name into the name of their signature weapons.
Give it a poem or rhyme to accompany it like the rings of LoTR Three Rings for the Elven-kings under the sky, Seven for the Dwarf-lords in their halls of stone, Nine for Mortal Men doomed to die, One for the Dark Lord on his dark throne, In the Land of Mordor where the Shadows lie, One ring to rule them all, one ring to find them, One ring to bring them all and in the darkness bind them In the Land of Mordor where the Shadows lie. That verse gives me goosebumps or like king arthur's excalibur Whoso pulleth out this sword from this stone, is right wise King born of all England.”
Maybe, make some people/characters talk about it or its components in awe as an introduction , something like this (I am tired and I am making random things here so don't judge, I am just trying to explain my point): "The core of the universal phoenix, strong and everlasting , the hilt from the eternal dragon, firm and unbreakable, the blade from the chaotic lands of the sunflare planet, smiting the evil and enemy for demons and deities alike, all together and coated in the blood of legions of immortal beings, and harnessed for thousands of years in the harshness of voids, one of a kind (you can go on) a weapon even the thunder god (lol) will be deemed unworthy of wielding, many will sacrifice their lives and the lives of their cherished ones to get a glimpse of it let alone hold it, but none is worthy as only the chosen deserve to bask in the glory of the one and only weapon of it's kind (name it)".
The only way to make a weapon unique is its backstory and how its retold by the population. The simple brass sheild used by peresus to defeat the Medusa.
Scenario 1 : Weapon breaks after one use and has to be fixed. This is actually great for OP weapons Scenario 2: Weapon requires the sacrifice of the life of someone or their soul or their loved one to work I seriously recommend Chinese xianxia stories like Chinese Paladin and Xuan Yuan Sword for research on weapons.
The sword have an important backstory. In The Heaven Sword and Dragon Saber, the weapons themselves not only treasured for their physical abilities but also the history and the secret that they represent. So make your weapon to be something that has important backstory or importance or something. So the Adamantium Weapon the character held might be the Sword of the Yellow Emperor or the Sword can only be wielded by the Moon Goddess-descended Maiden or something... You're the author. There are 2 way to approach it: The auteur path and the reader path. In the auteur path, you write what you want to write, reader be damned. In the reader path, you read in a way that is demanded by your reader, your intention be damned.
make them a growing weapon or something that grows along the protagonist, with the plots and other new elements in the story can be fit together. And don't always discuss about that legendary weapon so that you can change or alter its stats whenever there is a new plots or elements you want to add in your story