Vampire Survivors
125 Achievements
0-0h
PS4
Empty Tome
Hold 6 different weapons at once.
85.9%
How to unlock the Empty Tome achievement in Vampire Survivors - Definitive Guide
Instead of upgrading individual weapons while you level up within a stage, keep picking up different types of weapons and avoid all other upgrades that you are able to choose from.
As the description says, each time you level up or collect a treasure chest, pick a different weapon instead of leveling one up. Once you unlock enough weapons, you'll be using six different weapons in every run.