So I’ve been thinking, and I think Ouranus may end up being a legit spear or two handed scythe.
Reasoning: Oda likes his irony and I think each monster trio member will be in possession of an ancient weapon.
Luffy, a man who can’t swim, is going to lead the mermaid princess Poseidon (named after the god of the ocean) and an army of Seakings. The King of the Seas
Zoro, a man with no sense of direction, is going to sail Pluton (named after the god of the underworld) the greatest ship ever made. The King of Hell
Sanji, a man who refuses to use his hands, is going to hold Ouranus (named after the god of the heavens) the greatest weapon ever made. The king of the Heavens.
As for the item: scythe was the weapon Kronos used when murdering Uranus and spear was the weapon used by Judge (nicknamed the Garuda which is also seen as a king of heaven)