Once you have completed NeiR: Automata, has a couple of playthroughs, you might think that your weapons can only reach level 3 but there is a secret blacksmith which is able to upgrade your weapons to level 4.
The secret blacksmith is hidden away in a forest, named after Japan’s famous and greatest swordsmith Masamune. In NieR: Automata, he is an armoured robotic lifeform with the ability to upgrade your weapons past level 3 to level 4 (max level).
Having level 4 weapons also allows you to unlock Tools of the Trade and Inorganic Blade achievements. You will also be able to unlock Ending Y, which requires you to max out every weapon.
Where to find the secret blacksmith and upgrade your weapons to level 4
To find Masamune, the robot blacksmith who is the only person in the game who can upgrade your weapons you need to have access to the Forest Castle.
- From the castle’s Royal Chamber, head right and find the exterior broken bridge.
- Drop down through the hole in the bridge and gain access to the walkway below.
- Go right and interact with the all which will make you discover a secret hidden block, pull it back and it will show a path.
- Inside you will find Masamune and can upgrade your weapons.
His upgrades will cost you 10,000 to jump from level 3 to 4 and he has three weapons you can buy off him, Machine Sword, Machine Axe and Machine Spear.