In the warlock's Pact of the Blade feature description, it states the following:
… You can transform one magic weapon into your pact weapon by performing a special ritual while you hold the weapon. …
This indicates to me that only magical weapons can be bound in this way. Does that mean a silvered weapon, adamantine weapon, or even just a entirely mundane weapon is unable to be bound in this manner?
(My question was inspired by this question about summoning a pact weapon that's already silvered.)
Best Answer
Going by RAW, you are correct: only magic weapons
The part you're quoting from the PHB indicates that magical weapons can be bound like this. Also backed up in Sage Advice.
So unless the silvered/adamantine weapon is magical, you can't bind it as your pact weapon. As for mundane, you can create them using the Pact of the Blade feature, as described in the PHB: