The Ancient Meteoric Ore Greatsword is a new colossal sword in Elden Ring: Shadow of the Erdtree. Not only does it look cool, but its skill, White Light Charge, whooshes you forwards quite a distance in a stabbing motion, and then follows that up with an explosion—useful for quickly closing with an enemy that might be backing away.
Compared to many other Shadow of the Erdtree weapons, this one is pretty tricky to find. It's located at the end of a new forge-type dungeon, but getting to it isn't at all intuitive and you might be left scratching your head if you're coming up against a dead end. With that in mind, here's where to find the Ancient Meteoric Ore Greatsword.
The Ancient Meteoric Ore Greatsword is found inside the Ruined Forge of Starfall Past in Scadu Altus, but as mentioned above, even if you have that information to hand, actually locating the weapon is another matter.
The forge is found to the southwest of Moorth Ruins. Look for the Misbegotten enemies and you'll find the entrance between two lit braziers at the bottom of the slope. Once inside the dungeon:
You'll see the gate at the end of the room lower to let you through—note that it moves quite slowly. What you need to do is pull the lever again, jump off the ledge and over to the door as it raises and jump on top of it. Ride it up and you can reach the previously inaccessible platform on the opposite side.
From there, go through the door to find the altar of the forge in the room at the end. Examine it to receive the Ancient Meteoric Ore Greatsword and an Ancient Dragon Smithing Stone.
The sword itself requires points in strength, dexterity, and intelligence to wield it, though it scales with strength, dexterity, and arcane.