Which Crew Members Seek Ancient Weapons One Piece And Why?

If you strip it down to what's actually shown in the manga so far, the picture is pretty clear for two of the three weapons and still mysterious for the third. 'Poseidon' is currently Shirahoshi, the giant mermaid princess from 'Fish-Man Island'. She literally is the living weapon: her ability to communicate with and command Sea Kings makes her Poseidon. The series has shown her power in action and the World Government definitely knows how dangerous that could be. 'Pluton' isn't somebody breathing on a throne — it's a warship from the Void Century. The blueprints and knowledge around Pluton were made by Tom and tied to Water 7 and its shipwright lineage; Franky and the Water 7 crowd are the ones who know its history and location of the designs. In canon we haven’t seen a modern person actively 'wielding' Pluton as a deployed superweapon, only that the plans exist and are treated as nuclear-level dangerous. 'Uranus' remains the big blank page. Eiichiro Oda has hinted at a third ancient weapon, but its nature and controller have not been revealed in the story yet. That mystery is one of the hooks that keeps the speculation fires burning.

Tom's connection to the Ancient Weapons is one of those brilliant Easter eggs Oda loves to drop. As the shipwright who built Gol D. Roger's Oro Jackson, Tom had access to knowledge most couldn't dream of. The Pluton blueprints he later gave to Iceburg weren't just any schematics—they were the countermeasure to an Ancient Weapon. His role wasn't direct, but he was a linchpin in keeping the balance. What fascinates me is how his craftsmanship tied into the bigger picture—his ships carried legends, and his legacy shaped the fate of the world through Franky and Water 7.

I still get a little thrill thinking about the phrase "ancient weapons" whenever I flip open 'One Piece'—it’s one of those mysteries that feels like a slow-burn horror-mystery crossed with pirate fantasy. Canonically, we know about three names: Pluton, Poseidon, and Uranus, but Oda's habit of teasing and misdirection makes me suspect there are layers we haven't seen yet. On the practical side, I think there are at least a few possibilities: (1) fully unknown objects hidden away on lost islands or beneath the Red Line, (2) living weapons like Poseidon—i.e., beings or species that function as weapons, and (3) ancient technologies or systems (think energy sources, island-sized mechanisms, or even biological weapons) that don't fit our modern idea of a weapon but can be used to reshape the world. Vegapunk and the World Government’s secrecy over the Void Century suggest the tech and knowledge were either suppressed or fragmented. I like imagining one or two more ‘‘weapons’’ being revealed as social/biological forces rather than cannons or bombs: an ancient system that controls climate, or a race of tamed sea creatures that can reset ocean currents. Oda loves to flip expectations—Poseidon turned out to be a person—so keep your eyes open for things that look like ‘‘history’’ but operate like armaments. I’ll be re-reading the Poneglyph clues with a cup of coffee, because that’s half the fun: finding hints and arguing about them with friends late into the night.

My nerdy side lights up whenever this topic comes up, so here’s the clearest rundown I can give from what the manga and anime have shown so far. Poseidon is the easiest to pin down: she’s Shirahoshi, the giant mermaid princess living on Fish-Man Island. That’s explicitly revealed in the Fish-Man Island arc, and it’s canonical that Poseidon is a living weapon who can command Sea Kings. Pluton is tied to Water 7—Tom and the shipwrights built that warship during the Void Century, and the blueprints were preserved by the Water 7 shipwright lineage. The World Government’s interest in those blueprints is what led to Tom’s execution and a lot of secrecy around Pluton. Uranus remains the big mystery. Oda hasn’t given us a confirmed location or form for it, and theories range wildly: a weapon in the sky (maybe linked to sky islands), something hidden in or beneath Mariejois, or even a person like Poseidon. My gut says Oda will make Uranus thematically different from the other two—something unexpected that ties into the Void Century and the Final War in ways we can’t fully guess yet.

What hooked me wasn't just the giant reveals or the epic battles — it was how the ancient weapons turned the world of 'One Piece' from a playground into a pressure cooker. I think Oda introduced them to make the stakes feel genuinely global and old: these aren't just powerful tools, they're threads that tie the present to the lost Void Century. When Pluton and Poseidon come up, the narrative isn't yelling ‘power-up’; it's whispering about history, responsibility, and the sins of nations. On a personal level I love that they create moral ambiguity. As a fan who spends too much time arguing on message boards while commuting, I find it brilliant that a weapon so destructive can also be a symbol of salvation (think Poseidon and how it's tied to a living person). Oda forces characters — and us — to ask: who should hold that power, and why? That tension fuels character choices, alliances, betrayals, and the looming idea of a final conflict. Finally, the ancient weapons are a fantastic storytelling engine. They connect treasure maps, poneglyphs, and the World Government's paranoia into a single mystery. They're a narrative ladder Oda uses to climb from pirate adventures to world-rewriting events, and that's why they feel essential rather than tacked-on.

I still get a little chill thinking about the moment the story actually showed physical proof of one of those legendary things. In 'One Piece' the clearest, most on-the-nose confirmation is Poseidon: Shirahoshi on 'Fish-Man Island'. The moment she cries out and the Sea Kings respond, it isn’t rumor anymore — other characters react in real time, the island’s history lines up, and the power is demonstrated on-screen/page with witnesses. That single scene turned a myth into reality for everyone in the world of the story. For Pluton the evidence is a bit different and more forensic. We get blueprints and talk: Water 7 and the shipwright circles bring up a set of designs described as Pluton-class — a ship capable of mass destruction. Franky’s involvement, the blueprints appearing in the plot, and ultimately their deliberate destruction confirm that such a weapon concept really existed. Then there are the Poneglyph inscriptions and the archaeologists (and Nico Robin) who read names like 'Pluton', 'Poseidon', and 'Uranus' in ancient texts. Those inscriptions are big deal evidence because they come from the lost history itself. Uranus? Still a mystery. The world’s paranoia — the way the World Government violently suppressed Ohara, hunted down knowledge, and keeps extreme secrecy around anything that mentions those names — acts like indirect evidence. When an entire power structure treats something as existential, I take that as strong in-universe confirmation that those weapons aren’t just legends. Still, Uranus’ exact nature is left to speculation, which keeps the theorycrafting fun.

The Straw Hat Pirates from 'One Piece' are such a vibrant bunch, each with their own quirks and dreams that make them unforgettable. Luffy, the rubber-powered captain, is all about freedom and meat, while Zoro, the swordsman, relentlessly pursues his goal to be the world's greatest. Nami’s the navigator with a sharp tongue and even sharper skills, and Usopp’s the liar-turned-brave sniper. Sanji’s the chivalrous cook, Chopper the adorable doctor, Robin the archaeologist with a dark past, Franky the cyronic shipwright, and Brook the skeletal musician. Then there’s Jinbe, the fishman helmsman who brings wisdom and strength. What I love is how their dynamics shift—from goofy banter to heart-wrenching backstories, Oda makes you feel like you’re sailing with them. Their roles aren’t just functional; they’re emotional anchors. Like Franky building the Thousand Sunny as a symbol of their bond, or Robin’s infamous 'I want to live!' moment that still gives me chills. Even side characters like Vivi or the temporary additions like Law feel like part of the crew’s spirit. It’s rare to find a series where every member gets such depth, from fights to quiet moments sharing a meal under the stars.

I get a little giddy whenever this topic comes up, because 'One Piece' dropped the line about ancient weapons so casually but with huge implications. In-universe, the clearest case is 'Pluton' — the blueprints that Tom built and that later show up in Water 7 are explicitly described as a warship with the power to destroy an island. That bit of dialogue from the shipwrights and the way the World Government reacted makes it pretty canonical: Pluton can level an island if used as intended. 'Poseidon' is messier. It isn’t a bomb — it’s a living weapon: a descendant of the mermaid queen who can command Sea Kings. We’ve seen those creatures sink ships and cause massive coastal devastation in the Fish-Man Island arc, and if a Sea King or a coordinated group of them were ordered to attack an island’s shores or foundations, the damage could be catastrophic. 'Uranus' remains the wildcard; Eiichiro Oda hasn’t explained it yet, so we only have theories. So yes — at least one ancient weapon in 'One Piece' is explicitly capable of destroying islands, while the others could probably do similar-scale damage depending on how they’re used. The scary part is how the series hints that their combined use or strategic deployment could reshape the world map, which is why the World Government guards the Poneglyphs so jealously.

I've been chewing on this topic for years while rereading 'One Piece' and scribbling theories in margins of my old volumes. The ancient weapons aren't just flashy superweapons — they're narrative cogs that push every faction into motion. When you treat 'Pluton', the secret blueprints in Water 7, 'Poseidon', the living force in Shirahoshi, and the hinted 'Uranus' as more than just bombs, you see how they force characters to confront history, responsibility, and power. That tension is perfect fuel for a final saga where ideology matters as much as punch-ups. On a personal level, what fascinates me is the moral pulley they create: will the Straw Hats destroy systems or break tools to prevent abuse? Will the World Government cling to secrecy, or will exposure lead to revolution? The weapons tie directly into the Void Century and Joy Boy, so uncovering them pushes Robin's and the Revolutionary Army's arcs forward and forces everyone to choose who writes the next world order. I honestly think the final saga will hinge less on who can swing a sword and more on who gets to control the story about the weapons — and whether the world can accept a truth that might ruin the old peace. That kind of plotline makes me excited and slightly nervous every time I revisit the panels.