Bit of Aerosiderite is Weapon Ascension Materials used to ascend weapons, increasing the stats and max level. Higher-rarity materials can also be crafted with Alchemy by combining lower-rarity materials from the same group.
The coastal nations of Teyvat refer to the region beyond the protection of The Seven as the Dark Sea. It is said many defeated gods refused to live under the new order of The Seven, so they fled to remote islands and became evil gods. However, their powers came from the same source as Rex Lapis, separate from this all-devouring darkness.
How To Get
Bit of Aerosiderite is obtainable from crafting and dropped as a random reward from completing the Hidden Palace of Lianshan Formula domain near Mingyun Village every Wednesday, Saturday, and Sunday.
Bit of Aerosiderite can be crafted in the Alchemy table in Mondstadt or Liyue using 3 pieces of Piece of Aerosiderite.