[2020] My Weapon got removed

If it's a DLC weapon it might be just a case of relogging a couple times. Sometimes steam fails to report to the progression servers which DLCs a player owns (more so during these times of internet being consumed like mad!)

Originally posted by Rider of r------ded Lion Prince: Try to verify your game file or restart the game a cuple of time.
Steam is having a hard time remember who owns what DLC and not.

Steam remembers, so don't worry about DLC disappearing, but it's not the most reliable at reporting those DLC entitlements to us when you launch the game.