The .psb files are the particle effects I think. hugojackson18 said they were created using Fork Particle Studio. Might have a go at working out how to mod in additional effects via XML myself at some point.
Has anyone recently had a go with figuring out how to edit particle effects? Fork Particle Studio has a particle effects editor for mobile, but unfortunately I had no success importing the .psb files into it (although it does make an association with CiV's .psb files). I am certain it's a limited product from their actual editor and engine, but I was being hopeful it might at least allow me to view the effects if not edit them...