You can acquire gold weapons for your Shadow of the Tomb Raider playthrough. However, acquiring them is not possible inside the game itself. To get gold weapons you must register on the producer's website - "https://tombraider.square-enix-games.com/en-us". After creating an account, you must link your account on the square-enix page with your account on PlayStation, Xbox or Steam - depending on the platform you are using.
There are 4 gold weapons to choose from, and you can claim all of them if you wish. They have new, upgraded statistics. Each gold weapon does not replace the basic weapon that is available in the game, so you can change your weapon back and forth at any time. In addition, just as the basic version, the gold weapon can be subject to in-game improvements.
Recurve Bow Gold Edition
In order to get the Recurve Bow Gold Edition you have to, after linking accounts, like the official Tomb Raider fanpage on facebook. The bow should automatically appear in your inventory after a few hours.
Climbing Axe Gold Edition
If you want to acquire the unique, golden axe you need to follow the official twitter account named Tomb Raider. This way, after a few hours, the climbing axe will arrive in your inventory. This process can take up to 8 hours.
AB .45 Gold Edition
To get the Exclusive Gold Edition AB .45 you have to subscribe to the Tomb Raider channel on Youtube. Thanks to this you will gain access to the special golden pistol.
Vicar Mark II Gold Edition
If you subscribe to the official Twitch channel crystaldynamics you will receive a gold weapon - the Vicar Mark II. This process can take up to several hours, however, when it has been completed, the weapon will find its way to your inventory in the game.