I'll write some fiction and then describe weapons.
Some country or country on the planet has started the long, slow climb to becoming a K-level-1 civilization by exploiting space.
Doing this in the next few decades is economically crazy (the ROI is really, really negative for a long time), so I'll assume the nation has aligned around a religious requirement to move civilization to space.
To do this, they started building a self-reproducing manufacturing base in space.
The first problem with space is that it is expensive to get there. So if you can get materials in space and use them, they are going to be insanely cheaper.
Solar powered ion tugs were sent to get high metal asteroids. Decades of effort was put into building vacuum forges capable of refining the materials found. This provided bulk.
Simply insane improvements in 3D printing, and these bulk refined materials, permitted printing 3D printers with reasonable fidelity. These were then used to print further forges and more ion mining drones, which produced more raw materials.
All of this is automated or telepresence friendly. But for religious reasons, the nation wants humans to live in space. So settlements are built, and many many people die.
There is some modest conflict by rogue states and terrorist groups, so small amounts of defence tech is also included in the settlements (point defence drones and the like).
After many decades, there are some non-horrible rotating habitats with organic life in them. They are leaky as hell, so they rely on a constant stream of new volatiles from asteroid mining past the "snow line".
In this case, the best weapons that such a culture would have are the asteroid deliveries. Drop medium size rocks on the planet.
This lets you exploit the solar orbital energy of the asteroid and convert it to delivered KE on the ground. It is a long-delayed attack, but the energy amplification is really big.
Traditional attacks also work from orbit. You have line-of-sight to everyone, if a bit of air in the way. Just build cannons and shoot stuff down. Those cannons can be drone-controlled.
Defense against counter attacks is going to be hard. You might have to resort to nuclear interceptors; someone shoots a missile at you? Drop a nuke on it. It is plausible that the amount of uranium easily available in asteroids is probably higher than the Earth's crust, and nuclear reactors are a plausible source of power generation for a space civilization (especially for mining past the snow-line). (dumping heat is going to be as big a problem as making energy for space civilizations, which makes them less practical)
The book The Moon is a Harsh Mistress has another idea; launch rocks from the Moon. You can convert the KE of getting out of lunar gravity well into the KE of falling into Earth's gravity well. That is a modest amount of amplification. It suffers from a single point of failure problem; a launch facility on the moon has to deliver energy fast to efficiently get it off the Moon, which makes it a target.
Asteroid weapon launchers can be slow, and most of the heavy lifting can be done with a portable drone that pushes the asteroid, then detaches (leave a small engine on it for final aiming).
"Rods from God" have the problem that rods are not stable (making them not-tumble is going to be hard), deorbiting requires a lot of energy, wind resistance is really strong. If you rely on wind resistance to deorbit, your orbital energy is wasted on the atmosphere. And your "rod from god" is a lot like dropping a rock from a few 100 feet up. I mean, it hurts, but not that much. If you don't rely on atmospheric braking, then you need to put almost all of the KE of impact into the orbiting body to get it to stop orbiting.