I am so tired of people not understanding things and calling the Shadow Mantle "ERAM"
ERAM (Erasable Read-Adjust Memory) is how older engineers, typically outside of English speaking countries, referred to EEPROM - Electrically Erasable Programmable Read-Only Memory. It's a type of ROM that can have its data erased and reprogrammed. It's for things like firmware that don't need to update very often, compared to something like RAM that can be accessed whenever for whatever. You use it for things like embedded systems like autorun batches on USB sticks or firmware like previously mentioned. SSDs and USBs are based on EEPROM. In the west E-RAM was a common readout for ERROR - RAM, as in a memory error, usually overflow or null pointer. The name is a reference to the fact that you are deep in the system to allow this fight to happen.
The Knight even taunts Kris about "This" Shadow Mantle "that I'm holding." The Shadow Mantle isn't some haunted creepypasta videogame, it's an invader - If you forgot, every character in Tenna's versions of the games is being controlled by someone else. That goes for the Shadow Mantle too.
tl;dr ERAM is a technical term, not a name. How many fucking boss fights have the name of the boss as the full title of the song? I hate being in the same fandom as children.