Bloodborne weapons guide

Trick Weapons 

Hunter Axe, Saw Cleaver, Threaded Cane

Can be chosen as a starting weapon in Hunter's Dream. Also available for purchase from the Bath Messenger.

Beast Claw

Can be found in a random chest in an Ailing Loran Chalice Dungeon.

Blade of Mercy

Available for purchase from the Bath Messengers after obtaining the Crow Hunter Badge.

Burial Blade

Can be purchased from the Bath Messenger after defeating Gehrman, the First Hunter (NG+ only).

Chikage

Available for purchase from the Bath Messengers after joining the Vileblood Covenant.

Kirkhammer

Available for purchase from the Bath Messengers after defeating the Cleric Beast.

Logarius' Wheel

After defeating Martyr Logarius, you can pick up the Crown of Illusions on the rooftop. Wear this to initiate a cut scene and reveal a whole new building. Head inside, take the steps up, and check to the right of the throne to find the Unopened Summons. Give this to Alfred (the Cainhurst-seeking NPC found in the Cathedral Ward) to receive the Wheel Hunter badge, making the weapon purchasable from the Bath Messenger.

Ludwig's Holy Blade

Available for purchase from the Bath Messengers after obtaining the Radiant Sword Hunter Badge.

Reiterpallasch

You'll find this at the Forsaken Castle Cainhurst. In the first building you enter, check the back right corner for a chest containing the rapier.

Rifle Spear

This is found in Old Yharnam, during the section where you're fired upon by a machine gun. When you head down the wooden bridge above, take a right. At the back left of this rooftop is a series of ledges you can drop down. This leads to the inside of a large house; the Rifle Spear can be found on the top floor, up the stairs.

Saw Spear

Available for purchase from the Bath Messengers after defeating Father Gascoigne.

Stake Driver

Available for purchase from the Bath Messengers after defeating the NPC Gyula in Old Yharnam.

Tonitrus

This is found along the large street outside Yahar'gul Chapel. Wherever you exit, you want to make your way uphill. There will lots of blood enemies and large skeletons along the way, but at the very top of the street you'll find a corpse holding this weapon.

Proceed to Side Arms