Black Knight Halberd
From the Shaded Ruins bonfire in Shaded Woods, head up the slope and turn left. Enter the crumbling building, go downstairs, and exit to a small, sandy area. Continue down this path to eventually reach a petrified enemy. Use a Fragrant Branch of Yore to cure him, then take him out to keep moving forward. Leap the gap of the broken green bridge just ahead, and you'll find a chest containing this weapon.
Blue Knight's Halberd
Received after killing Blue Sentinel Targray in the Blue Cathedral.
Can be traded for the Dragonrider Soul with Straid of Olaphis at the Straid's Cell bonfire in The Lost Bastille.
Found in a Pharros' treasure room in the Shrine of Amana. See our Pharros' contraptions guide for more information.
Old Knight Halberd
From the Tower of Flame bonfire in Heide's Tower of Flame, head down the spiral steps. There's a second large knight along the narrow walkway. Past him are several corpses, one of which holds this.
Old Knight Pike
This is found near the Mines bonfire in Harvest Valley. Continue down the path, then take the left path at the open area with the wooden tower in the middle. Over here, a large enemy will burst through the rusted wooden planks. Engage, then trick him into breaking the other set of planks behind him. This gives you access to several corpses, one of which holds this weapon.
Found near the Lower Earthen Peak bonfire in Earthen Peak. When you cross the long bridge, make a right and take the stairs at the end of the hall. Follow the ledge this leads to find a chest containing the weapon.
Can be traded for the Skeleton Lord's Soul with Straid of Olaphis at the Straid's Cell bonfire in The Lost Bastille.