Dungeons & Dragons immerses players in a fantasy world like no other game, and few fantasy tropes are as awesome to imagine first hand as wielding a powerful legendary weapon that can save the world. As Player Characters level up, both the players and their Dungeon Masters will be looking for ways to make them ever more powerful -- and eventually getting their hands on the perfect weapon is a necessity.
To stay alive against the most challenging dungeons and dangerous dragons the world has to offer, every character will need the right tool for their class. Every campaign is different, but with a few tweaks these legendary items can be incorporated into any campaign.
Obviously, martial classes are going to be most inclined toward finding powerful magic weapons, but part of what's great about D&D is that others can get in on the fun too. The skill proficiencies are broad enough that most classes at least have some dip into weaponry that they can enjoy. That means that the most common magic weapon fantasy trope, the legendary sword, is solely meant for the party's master sword user. There are plenty of magic swords to choose, meaning there's a good fit for anyone who wants one. However, certain ones stand out.
Mechanically, Blackrazor is quite possibly the best sword of the game. It grants a +3 bonus to attack and damage rolls, but the real clincher is its passive abilities. When it slays a creature, it consumes its soul, granting the wielder temporary hit points along with advantage on attack rolls, ability checks and saving throws. The sword also grants awareness of most all creatures in the wielder's surroundings, and comes with its own sentience and personality that allows it to cast Haste without occupying the wielder's concentration.
It's the ideal sword, though it can only be used by a character of a non-Lawful alignment. Those characters should instead look to the Vorpal Sword, which also comes with attack bonuses and a constant possibility of instantly ending a fight by beheading.
Swords are far from the only weapons in the game. Those looking to deal blunt damage or shoot arrows from afar will want their own choices. Barbarians and Rangers can get a lot of use out of the Javelin of Lightning, a ranged weapon that lets a character act like Zeus once a day to deal massive damage. Any dwarven character would be honored to wield the Dwarven Thrower warhammer that deals extra damage to giants and returns to their hands after it is thrown. As for archers, there are few bows cooler than Mythic Odyssey of Theros' Ephixis, which has various magical abilities in addition to suffering no disadvantage even at 320 feet.
Spellcasters should not feel left out either. Warlocks, Sorcerers and Wizards need a spellcasting focus to work their magic, and to that end, they can't do better than a Staff of Power. This grants a +2 bonus to Armor Class, saving throws and spell attack rolls. Armor is a hot commodity for spellcasters, but even more valuable are their spell slots. The Staff of Power comes preloaded with some of the best defensive and offensive spells in the game, making it the ideal weapon for any caster.
These weapons together comprise one of the mightiest arsenals a Dungeons & Dragon character could assemble, but they're all pulled from different books and parts of the world that may leave DMs and PCs alike scratching their head about where to find them. The secret to finding the perfect weapon in any game, first and foremost, is communication. If you're a player who finds a certain weapon appealing, talk to your DM about possibly working a quest into the campaign that could earn you that weapon.
Quests to gain powerful items are the best way to work powerful artifacts into a story. It makes them memorable and important so players will remember wielding their trusty weapon for years to come. A PC's god could grant them the quest to hunt down the weapon, or an ancient prophesy could foretell that it will prove a necessary piece in saving the world. Make the weapon feel special and the quest to attain it memorable, and it can become as much a unique part of the character wielding it as anything else.