Beryllium is a mental internal pushing metal. In Allomancy, when burned, it enhances one’s sense of judgement or righteousness, and allows one to see what the most “ethical” path is. A beryllium misting is known as a Judge. In Feruchemy, it stores memory. This is different than copper, which stores individual memories, instead Beryllium stores how likely you are to forget something. When storing, the user becomes very forgetful of things, but when tapping the user is much better at remembering things. A beryllium Ferring is called a Librarian. In Hemalurgy, beryllium steals one’s sense of righteousness, and one becomes more ethical if they have a beryllium spike.
Beryllium copper is a mental internal pulling metal. In Allomancy, when burned, it enhances one’s hearing in ways tin does not, when flared it grants perfect pitch, otherwise it allows one to understand the music better and hear individual notes. A beryllium copper misting is known as a muse. In Feruchemy, it stores one’s hearing and understand of music. A beryllium copper Ferring is known as a Singer. In Hemalurgy, it steals one’s understanding of music, but this is most useful when it is taken from someone with perfect pitch.
Note: when I say “understanding of music,” I do not mean understanding in how the word is usually thought of. Instead I mean better hearing the music, and being able to separate individual notes or instruments, and with some training be able to figure out what those instruments are.