The most basic and most versatile calligrapher's implement, gifted to Carl by Milk alongside a wineskin of permanent ink.
Milk hands Carl a fountain pen immediately after the Stayfast Ink. The item text calls it the most basic of all calligrapher's implements and muses on how much grief and suffering — and how much joy — such things have caused, noting that the pen being mightier than the sword is one of the few human metaphors the system believes universally true, especially since swords are terrible, barbaric weapons.
It then challenges the owner directly: will you write a book that changes everything, invent a new take on hucow fiction, or just literally stab someone in the neck with it again? The gift arrives at the same moment Milk mentions Book of Voodoo and the way anything written in it propagates to every existing copy.
A plain fountain pen, the simplest tool in a calligrapher's kit.
The writing implement Milk arms Carl with for whatever he decides to write.