In One Piece Odyssey Usopp’s experience and skills will be taken from him. In order to get them back, you’ll need to locate 40 cube fragments scattered around Waford Island. Below is a guide on where to find his cube fragments in Marineford. You’ll receive the Cube Collector: Usopp trophy/achievement for finding all of his cube fragments.
Marineford City Area
Crumbled Ground
This cube can be found behind a bush past the bridge Franky needs to repair. The bush will be to the right between 2 trees.
South Town
This cube can be found in the southwestern part of South Town, west of the bell on the walkway.