Vampyr

All credit for this guide goes to SnowNinjaRaccoon (DK) & PowerPyx from PowerPyx.com who provide a complete guide to finding all collectibles and all weapons in Vampyr. This guide covers all 12 one-handed and 8 two-handed in chapter order, although the guide they created also covers all collectibles and ranged weapons as well.

Prologue:
[One Hand Weapon #1] Used Machete
You will run past it at the very beginning of the game. You will have to pick it up in order to protect yourself.

Chapter 1:
[Two Hand Weapon #1] Used Scythe
After passing the hideout on the higher floor you will cross a bridge and enter a tunnel. Jonathan will mention fresh blood. A bit further down the tunnel, you will find the scythe.

[One Hand Weapon #2] Used Bludgeon
Granted for Defeating William Bishop.

[One Hand Weapon #3] Used Hacksaw
Hospital, 2nd floor.

Chapter 2:
[Two Hand Weapon #2] Common Barbed Cudgel
Found at the start of the Sewer Section (you go there during the story).

[One Hand Weapon #4] Used Hatchet
Whitechapel District, Northwest, Second Floor of the Warehouse with a Sewer Monster in it.

Chapter 3:
[Two Hand Weapon #3] Common Mace
Hideout in Sewers (area where you meet Bridget).

Chapter 4:
[One Hand Weapon #5] Remarkable Saber
Granted for defeating Doris Fletcher.

Chapter 5:
[Two Hand Weapon #4] Common Axe
Found at the end of the sewers section with the Leon Augustin Boss Fight. After the part where you use the 3 valves to raise/lower the water. After lowering the water and making it to the other side there’s a bridge you can teleport up to (there’s a lady held hostage in the tunnels here called “Louise Teasdale”). It’s just before the sewer exit.

Chapter 6: Important: Make a manual Save Game Backup at the start of Chapter 6! See spoiler:
[One Hand Weapon #6] True Dragonbane: This weapon has it's own guide and achievement associated with it and is likely the most difficult item to unlock in the entire game:

[One Hand Weapon #7] Clay’s Hatchet
Kill Clay at the hospital.

[One Hand Weapon #8] Rakesh’s Surgical Saw
Embrace Rakesh in Hospital and loot his chest.

[One Hand Weapon #9] Newton’s Saber
Embrace Newton in Hospital.

[One Hand Weapon #10] Seymour’s Bludgeon
Embrace Seymour in the Docks.

[One Hand Weapon #11] Louise’s Machete
Embrace Louise in West End.

[One Hand Weapon #12] Archer’s Hatchet
Get it from Archer in the Docks.

[Two Hand Weapon #5] Joe’s Barbed Cudgel
Embrace Joe Peterson in Whitechapel and open a chest in Harry Peterson’s House (2nd Floor).

[Two Hand Weapon #6] Booth’s Axe
Embrace Booth in the Docks.

[Two Hand Weapon #7] Rodney’s Scythe
Embrace Rodney in the Sewers (Docks Event on a map).

[Two Hand Weapon #8] Samuel Connor’s Mace
Kill Tippets in Hospital, Loot Tippets, Loot his Desk/Drawer/Locker (don’t remember which one it was) in Doctor’s Room in Hospital. With the small key head to the basement of the morgue where a corpse lies on the table. Loot the chest there for the weapon.

Welcome, Here is videos walkthrough for all weapons and collectibles, Enjoy

Credits for youtube video goes to PowerPyx channel