Detecting and intercepting kinetic weapons could be very very difficult. You shape them like stealth bombers, paint them in a radar absorbing coating and launch them at Mach 10 or so. Especially since you have nearly unlimited range to fire from and gravity assists to achieve funky angles of attack. A projectile of depleted uranium with a titanium weave penetrating core would be there with nuclear weapons for destructive power and harder to stop.

In a universe where the Rods From God are an everyday threat, planetside military bases would be easy pickings, so spacefaring craft with erratic trajectories would be preferable. (You could have a plot arc about someone stealing the navigation software that adds randomness to a ship’s course to avoid long-range ballistics)