Meteorite Staff is one of the best weapons and one of the best staves or (staffs) in Elden Ring. While Meteorite Staff is not precisely meant to be acquired early on, getting it as early in the game as possible is highly recommended if you started the game as an Astrologer or plan on developing a mage build.
Meteorite Staff location
You will find Meteorite Staff at Swamp of Aeoniain Caelid. You can ride to the swamp, but most players get there by triggering a booby trap on a chest early in the game, which teleports them to Selia Crystal Tunnel. There is a Site of Grace in Selia Crystal Tunnel, so if you have discovered it, you can teleport there anytime.
Once there, you will have to travel southwest to get to the Street of Sages Ruins. Some poisonous mages and flowers guard the area, so you will have to proceed with stealth and caution. You can see the exact location of the staff on the map below:
You will have to get to the southwest end of the ruins, where you will find a structure with a small staircase on it. It is easy to spot as the building is the only tower in the ruins. However, you should approach its entrance carefully as you will find three poisonous flowers inside the tower.
Once you get rid of the flowers, you will be able to access the corpse of a mage half-hanging out of the window:
Loot the corpse to acquire Meteorite Staff. Keep in mind that the location is quite challenging early in the game, but there are two Sites of Grace close to it and a Stake of Marika, so you don't have to worry about getting things right the first time.
While Meteorite Staff does not come with a Weapon Skill, its pedestrian requirements of 18 in Intelligence and 6 in Strength, along with its S-scaling in Intelligence, make it a powerful weapon for Astrologers and other mage builds.
If you get it, you will use it for quite a while, as the power of your sorceries will greatly boost.