I've decided to make a Uranus theory because I have the feeling we're going to find out what it is soon. I think the moment Robin slaps her eyes on the Poneglyph in Kaido's dungeon the big mystery will be over. So I want to have a go at figuring out what it actually is before that and basically place my bet since I've always shied away from giving a solid opinion before because we know nothing about it except it's name. Of course the Poneglyph could be about something else entirely but whatever. I'm not ruling out weather device and if that's the conclusion I arrive at then so be it. But I'm hoping it's something else if for no other reason than everyone's guessed that for years. Starting this theory I have no idea what I'm going to decide on so I'm working this out in real time as I write. Disclaimer: since we know nothing about it everything I write will very like be wrong. Ok so here I go...
What We Know:
It's name is Uranus and it's an ancient weapon. The person who gave us that information was King Neptune the king of Fishman Island and father of another ancient weapon Poseidon. We know from Dr Clover that the ancient weapons are each considered powerful enough to pose a threat to the world. So whatever it is it's powerful. We know that it was considered important enough by whoever wrote the poneglyphs to preserve it's location and identity on a poneglyph for future generations. So we also know they believed it will have an important role in whatever their purpose in creating the poneglyphs was. We all guess it's to fight the CD's but I'm stating absolute confirmed information right now. This also means that it existed 8 or 9 hundred years ago. So it has to be something that can either survive that long or a new version of it can be made available. Shirahoshi is a woman who genetically inherited her power as Poseidon. She is not the same Poseidon who lived 800 years ago. Pluton is a ship which had blueprints and can be rebuilt. It is possible that the original is still around. And we know that having Uranus and the other weapons during the void century was not enough to prevent whatever happened that made creating the poneglyphs neccessary. That's all we know.
Things We Can Reasonably Assume:
The poneglyphs were made by the people of the Ancient Kingdom in response to their defeat and the realisation that the 20 kingdoms were going to erase all knowledge of them from history. They wrote down the true history and the esistence and locations of their best weapons on huge indestructable stones in the hope that one day someone, most likely their descendants, most likely the D clan, who don't even remember them, would read their story and take up their fight against the CD's and win. They may be waiting for someone in particular judging on Whitebeard's dying speech. The fact that Uranus is one of the weapons mentioned on the poneglyphs suggests it was owned by or affliated with the Ancient Kingdom.
Pure Speculation Time:
The only way I can think of to suss out what Uranus may be is by comparing the other weapons and thinking how it could fit in with them.
1. Poseidon and Pluton are both sea orientated. Poseidon is a giant mermaid and Pluton is a ship. Shirahoshi can come on land if she wears a bubble ring but her power is with Sea Kings so she would have to be in or near the ocean to use it. And Pluton is a ship so... >->
2. In the present they both have a connection to Fishman Island. Shirahoshi is a mermaid and the plans to Pluton were kept by Tom who was a fishman too. I've always wondered why of all the people on water 7 why the guy originally in possesion of the Plutons blueprints was a fishman. Neptune knows about the weapons. It makes sense he knows about Poseidon but why the other two as well? Joyboy left a message on a poneglyph for the previous Poseidon as well who was obviously a mermaid too. I think the fishmen are a huge connection to void century. Not just Shirahoshi but also the Noah and Ottohime prophsysing a man who will guide Shirahoshi. Etc. They know a lot. The voice of all things. Uranus being connected to them as well I don't think is far fetched.
3. They both are more powerful versions of things that already exist. All fishmen can communicate with fish. Poseidon just does it on a bigger scale with Sea Kings. Maybe because of her enormous size, maybe not. I believe Neptune can talk to sharks or whales and he's bigger than the average fishman and I think Shirahoshi is even bigger than he is. Ships are definately common in One Piece. Pluton is just a really powerful one.
4. As already stated they are things that can last over time because if something happens to the original it's possible for another Poseidon to be born or another Pluton to be built.
5. Also already stated they both have the potential to be massively destructive. I'm just trying to get down all their similarities. Sea Kings definately can take out ships and maybe islands, I don't remember. Pluton can definately take out both. If it can kill an island it should be able to kill a ship.
6. We knew about fishmen and their ability to talk to fish before fishman island. And we met Shirahoshi before it was announced that she was Poseidon. We knew since Alabaster that Pluton was a warship and we were introduced to the island of shipwrites and the idea of the ship spirits (Merry had a mind!) before we learned about Plutons blueprints.
7. Intelligence. Shirahoshi is undoubtably intelligent. We know from the Merry that ships can develop spirits. We don't know if Pluton has a soul but we know it's the most powerful warship in the world so I think it'd be strange if Merry could develop a soul but it couldn't. We also know Tom and Franky have a philosophy of loving your ship no matter what so even if the original Pluton doesn't have a soul any ship made by Franky has a good chance of developing one. (Go Sunny!)
Ok so this is pure speculation.
So ever since Skypea I've had the idea of the sea being a country. If this is the case then ships would be the most common mode of transport in that country and of fighting. If the AK was the sea then I imagine they were people who lived on ships living a pretty nomadic life sailing from one island to the next, picking up what they needed and experiencing new cultures etc. So when these ship people AKA the D's went to war Pluton would have been the best and most powerful weapon they could produce. They all had ships but it was their very best kick-ass ship. Imagine it spearheading their armada. When the 20 kingdoms looked out to sea there were a thousand normal ships and then front and centre the impressive sight of Pluton. It was their best contribution to the fight and when their enemies saw it they knew the D's had come and they meant business. Not only was it powerful it was representative of them, the nomadic people who lived on ships. The same with the fishmen. I think we can safely assume the fishmen were in the fight. Poseidon was a person with an intelligent mind. The D's wouldn't have been able to "use" her. They would have needed to cooperate with her. The fishmen must have had an equal stake in the war for her to participate. They all could talk to fish but she was the only fishman who could control Sea Kings. So she was the best weapon the fishmen had to give to the war and she was the biggest fishman ever. Anyone looking at her would know the fishmen had come to kick-ass. So that leaves Uranus.
I'm gonna do a quick recap of trates I think Uranus could have:
1. Destructive power on par with the other weapons.
2. Sea orientated.
3. Connected to the fishmen somehow. This is a maybe.
4. Can be rebuilt or reborn.
5. Is representative of a third group of people who fought in the void century.
6. Is a more advanced or ultimate version of a common power or technology that those people used.
7. Something that may already have been introduced to us that we may not yet know is connected to Uranus.
8. Possible intelligence. This is a maybe.
Ok so the first thing to address is who were the third group of people who fought?
1. Kozuki Clan - They wrote the poneglyphs and Momo has a version of the voice of all things that lets him command Zunisha. I believe these 2 things are linked. Wano is also an island that lives beyond the control of the WG.
2. Tontatta - They were the ones who made it possible for sunlight to reach Fishman Island. They were there during the void century.
3. Shandorians - They were there during the void century and they have a poneglyph. They also live in the sky and Uranus of mythology was god of the sky. I already have a theory that the traditional names of the gods are an indication of the weapons' locations not their power.
4. Giants? - I don't know. I just think once we reach Elbaf we could learn something important about their role during the void century that hasn't been revealed yet.
Honestly I leaning towards the Kozuki Clan and Zunisha. The Tontatta do plants. I can't imagine a plant weapon on par with the power of Poseidon and Pluton. And I can't think of anything the Shandorians had that could be the weapon either. It's possible in future they could provide flying machines or maybe a very explosive dial but I don't believe they had them during the void century.I'm not ruling out Giants but I want to stay with the known elements. So that leaves the Kozuki Clan. I know I'm not the first person to think this and the first time I heard it I was like yeah right. But reasoning it out I'm starting to believe it. I'm starting to think that the voice of all things is the key here. If Momo could control Zunisha she could do a lot of damage. And if you take into consideration that she committed some crime centuries ago that she's been cursed to walk the sea forever for. What if she's the reason the D's lost? What if she ran away or made the wrong decision and acted of her own accord and caused them them to lose?
Let's go down the list.
I. Destructive power on par with the other weapons - Check
2. Sea orientated - Check
3. Connected to the fishmen - Check. The Kozuki Clan must have written the appology to Poseidon or taught JoyBoy how to write it 800 years ago.
4. Can be rebuilt or reborn - Check. There could be more baby giant elephants somewhere.
5. Is representative of a third group of people who fought in the void century - Check. If the Kozuki Clan was known for having the voice of all things then controlling Zunisha would have been a display of that power.
6. Is a more advanced or ultimate version of a common power or technology that those people used - Check. If other people who have the voice of all things can only hear Zunisha but Momo can command her.
7. Something that may already have been introduced to us that we may not yet know is connected to Uranus - Check
8. Possible intelligence - Check. Zunisha is definately intelligent.
However, maybe it's not neccessarily Zunisha who's Uranus but Momo or this ultimate version of the voice of all things? But honestly this is the best guess I can make as to what Uranus is. By the way? Uranus from mythology was known as the Rainmaker and Zunisha sprays water on the Minks twice a day. So maybe? Also I made a previous theory that Uranus would somehow power Zeus and make him stronger. Well Zunisha is the home of the minks, all of whom can generate electricity. What if the minks fill Zeus up with electrity and make him epically powerful, all while riding on the back of Zunisha? Just a thought. So yeah. That's all I've got. I wish I could arrive at something completely original but I hope I reasoned it out well enough to show I wasn't copying anyone. Hope you enjoyed. Let me know what you think. Sorry if it's messy. I thought working a theory out in real time would be fun. And it was =)