NieR: Automata - How To Fully Upgrade Weapons | Secret Lvl 4 Blacksmith

Even after completing the story through multiple playthroughs, it might seem like weapons can only be upgraded to Level 3 in NieR: Automata. It turns out that isn’t the case — there’s a coveted level 4 blacksmith hidden away in the forest. He’s extremely easy to miss, even if his hidden location seems totally obvious in hindsight.

The secret blacksmith is called Masamune, named after Japan’s greatest swordsmith. The armored robotic lifeform might not be the genuine article, but its better than any of the other Blacksmiths in the game. His most important function is, easily, the ability to upgrade weapons to Level 4. Yeah, it sells some cool items, too.

Level 4 is the highest level of weapon upgrades, and is required to unlock the “Tools of the Trade” and “Inorganic Blade” trophies / achievements. It’s also a requirement for Ending Y — you’ll have to max-out every single weapon to get that one.

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How to Upgrade Weapons To Lvl. 4 | Secret Blacksmith

To find the only Blacksmith that can upgrade weapons to Level 4, Masamune, you’ll need to access the Forest Castle. This area can be revisited later.

Level 4 Blacksmith Location:
1. From the Forest Castle: Royal Chamber, go right to find the exterior broken bridge.
2. Drop down through the hole in the bridge and land on the walkway below.
3. Move left and interact with the wall to discover a hidden block. Pull it back to reveal a secret path.

The Forest Blacksmith can only upgrade Lvl 3 weapons to Lvl 4. It costs 10,000 in-game currency to upgrade.

His store carries three weapons; Machine Sword, Machine Axe, and Machine Spear. These are all weapons wielded by machine lifeform enemies.

Source: [1]