We all need a weapon like Eight the Sparrow in our lives, especially in an apocalypse.
In a game about surviving innumerable waves of monsters, you're gonna need all the help you can get. For some, it helps to have a load of magic dust by your side, others find comfort in having (not) Simon Belmont as their ally.
Some, however, find everything unnecessary except for a good old-fashioned pair of six-shooters. Fortunately, in Vampire Survivors' case, you can go guns blazing in the form of the blue-handled pistols Eight the Sparrow.
In order to unlock Eight the Sparrow, you'll need to beat a pretty simple task: Find Pugnala Provola and survive a full 15 minutes with her in a game. Provola is an unlockable character, so in order to even work on getting the weapon, you need to find her. Fortunately, she is pretty easy to locate, as her coffin can be unlocked on the first map.
All you need to do is work your way through the level Mad Forest. Once you find her coffin on the stage, and defeat the enemies surrounding it, then Provola will be unlocked.
Once Provola is freed from her coffin, all you need to do is play her in a round, and survive a full fifteen minutes, and then Eight the Sparrow is unlocked. After that, you have a brand new pair of powerful pistols to mess around with.