After getting the Weapon you have to get the Second piece of (Chester Morgan’s Letter). Move forward by going down. Defeat the enemies and get out of the cave and follow the path within the river to the left side. A little far within the tree you will face some enemies. After defeating them move forward. A little far you will see Edgar.
Meeting Edgar
After that Jesse uses the zapper which will show him the blocked wall and source (Glamour Seals) to destroy. The red line shows you the Glamour which is inside the blocked cave. You need to open the gate of that cave so you can reach the glamour. Go to the left side climb up and shoot the target to open the first gate. Now go to the left side of the cave. Use the chain to climb up and destroy the first glamour seal. Then go to the high point in front of the cave and shoot to destroy the second glamour.

Where To Find Chester
Use the zapper in front of the blocked path to destroy it completely. Move forward through the field and defeat the enemies. You will face multiple big enemies which will take time to defeat them.