Among the batteries, tyres and other junk you can fish up in the sewer system between the City Ruins and the Amusement Park, you can find the Iron Pipe used by Nier. Credit for this find goes to a post by D87 of GameFAQs.
Here is its short description:
A common iron pipe.
Here is its long description:
A rusty iron pipe covered in the vital fluids of machine lifeforms.
Here is a table of the stats I can currently see. Please leave a comment if you can fill in the missing info or know the locations of Large Gears and Machine Arms for upgrading.
|Lv||Attack||Combo||Special Ability 1||Special Ability 2||Weapon Story|
|1||30-220||Lt 2 Hv 1||–||–||Dad, if you’re cold, I can give you my hat. You’re the best father in the world, after all.|
|2||54-396||Lt 3 Hv 1||Critical + (Adds a critical-hit effect.)||–||Dad, if you’re hungry, you can have my cookie. You’re my favourite person in the world, after all.|
|3||84-616||Lt 4 Hv 2||Critical + (Adds a critical-hit effect.)||–||Dad, if you’re scared, I can sleep by your side. You’re my closest friend in the world, after all.|
|4||114-836||Lt 5 Hv 2||Critical + (Adds a critical-hit effect.)||High Stun (TBD)||TBD|
Edit: I have uploaded the image which accompanies the weapon story.