Night's Edge

Each swing throws out a ring of purple energy that reaches past the sprite, plus a second arc that sweeps toward your cursor. The hitbox is far larger than the sword looks and it covers ground behind and above you as well as in front. Each of the two auras catches a couple of enemies, but one enemy cannot be hit by both, so the extra reach pays off against crowds rather than against a single target. In an unlit room the auras light themselves, which makes it easy to see what you are actually connecting with.

This is the melee weapon to bring to the Wall of Flesh. The reach lets you catch two of its parts at the same time from the middle of the corridor, and the aura keeps the Hungries hanging off the front from ever reaching you, which is the thing that usually kills a melee character in that fight. Lay a long flat bridge across the Underworld and the sword handles the rest.

The four component swords are one from each dangerous place in a pre Hardmode world: the Jungle, the Dungeon, the Underworld, and whichever evil biome your world generated. The Dungeon piece is why Skeletron normally has to die first, and by the time you have all four your pre Hardmode checklist is essentially finished. Look closely at the particles it sheds and you will find all four donors mixed in, one pattern each.

Two secret seeds break that order. A drunk world generates its locked gold chest above the depth where Dungeon Guardians patrol, and that chest reliably holds a Muramasa, so the sword can be finished before Skeletron ever dies. In a zenith world the Dungeon enemies drop nothing that early, but ordinary chests and pots still generate inside the walls; break in with a Molten Pickaxe and take a Golden Key off one. A Starfury is a reasonable weapon for that trip.

Legendary is the roll to chase. Do not sell the sword when it stops carrying you, because it is the base of True Night's Edge, which in turn feeds the Terra Blade. If you would rather have a component back, Shimmer breaks it into its parts and the evil sword you get depends on your world: Light's Bane in Corruption, Blood Butcherer in Crimson. Drunk worlds contain both evils and flip which one you receive each in game day.

It held the title of strongest sword in the game until Hardmode weapons arrived, and it is still the strongest one you can make before the Wall dies. The auras will also smash pots through a wall even though they cannot damage anything on the far side, which is a fast way to strip a room you have not opened yet.