Weapons technology in the Honorverse is hugely capable, and starships must carry similarly impressive defenses.

Starships are immune to attack from above or below due to the impeller wedge. As long as the impellers are powered,a ship can project "sidewalls", weaker versions of the wedge, as shields on either side. Sidewalls are non-ablative, gravitic stress bands, and thus weaker lasers and grasers are bent away, or refracted like light is when it passes through denser mediums. In this instance, the focused light is bent by the intense gravity in the sidewall. Sidewalls are invulnerable to non-massless/lightspeed weapons as they would be destroyed by the gravitic shear caused by the sidewall. When the series begins, it is impossible to close the bow or stern of the wedge with a wall; to do so would prevent any acceleration. The Manticoran Shrike-class LAC is fitted with a bow wall, which is only meant to be raised for short periods during its attack run. Later, the Edward Saganami-B class heavy cruisers are equipped with stern walls, which reduce but do not entirely stop acceleration. The Edward Saganami-C type also has a bow wall, of a special "two-phase" type. A smaller, inner wall can be raised independently of the main bow wall. The smaller wall does not completely seal the forward aspect of the wedge; it only protects against attacks from directly ahead. However, it does not interfere with thrust or maneuvering.

Against lasers and grasers, the sidewall is the first line of defense. Missiles can be stopped by other measures, including countermissiles, point defense lasers, and sensor jammers.

Ships are also protected by many layers of armor that alternate between ablative composites that absorb energy from energy weapons and solid anti-kinetic layers. The side armor of a superdreadnought is over a meter thick. Inside, there are more armored bulkheads. Even with this tremendous defense, at close range, the energy weapons of any starship are more than enough to destroy a larger ship.

Though this is rarely mentioned, starship hulls are "grown" using nanotechnology, and can be repaired in similar fashion.

The ultimate in personal defensive equipment is battle armor, which resembles the powersuits in Starship Troopers. This type of powered exoskeleton is invulnerable to direct hits from chemical-explosive grenades.