Source: Explorer's Guide to Wildemount

Weapon (dagger), rare (requires attunement)

This weapon is a magic dagger disguised as a sewing needle. When you hold it and use a bonus action to speak its command word, it transforms into a dagger or back into a needle.

You gain a +1 bonus to attack and damage rolls made with the dagger. While holding it, you can use an action to cast the Mending cantrip from it.