The Shattered Lands
Magic weapon (any sword, rapier, or dagger), very rare
Prized by paladins and inquisitors who hunt down fiends, truesilver blades are often delicate looking and carry angelic motifs, such as feathers, musical instruments, and inspirational scripture.
A truesilver blade counts as a silver weapon. You gain a +1 bonus to attack and damage rolls made with this magic weapon. When you hit a fiend with it, the fiend takes an extra 2d6 radiant damage.
When you roll a 20 on an attack roll made with this weapon against a creature native to a different plane of existence than the one you’re on, it must make a Charisma saving throw (DC = 8 + your proficiency bonus + your Charisma modifier) or be banished to its home plane.