I don't know this but it makes sense that planets and stars are close to spherical because gravity isn't a "directional" force, being a curvature of space/time. Most celestial bodies arn't perfect spheres due to other forces. For example the rotation of the earth causing a bulge at the equator.
The way I see it, if you can control gravity, it doesn't really matter what shape your ships or weapons are. Spiral them like a corkscrew. Have them in seperate pieces. Make them inside out. Or all of the above
