The first Fallout 4 DLC, Automatron, is a new robot-heavy chapter in the game that allows the player to build robot drones to act as companions or settlement workers. This is done through the new Robot Workshop, where robots can be built from scrap or salvaged for components and given bizarre and powerful modifications, most notably the weaponized arm attachments.
Curious about their range and effectiveness, I set out to make a robot with each attachment and test its mettle in combat, using console commands to unleash waves of enemies. During the events of the DLC, when it comes time to place the Robot Workshop and start building an Automatron army, the game directs you to Spectacle Island, giving your drones a wide open space in which to roam. Since this area also requires the sprawling protection only they can provide, it is an ideal space to try out the many arm modifications available.
There are 31 different arm attachments for the Automatrons made at the Robot Workshop station, and in terms of overall value they range from “worthless” to “cool but pointless” to “I could blast the face off a Deathclaw with this thing.” With a few keystrokes I unleashed Deathclaws, Ghouls and Raiders on a robot army comprised of 20 different arm attachment customizations, and after observing how they fared, factored this into a list gauging the value of each.
Perhaps predictably, the melee type mods offer the least amount of protection and combat effectiveness, quickly succumbing to physical damage. The performance of the rest varied depending on which type of enemy was spawned, but universally the robots modified with double Missile Launchers worked the best. When making your robot, try to pair its attachments such that they complement almost any combat situation, taking into account both armored and unarmored enemies.
Here are all the attachments available, listed in order of worst to best.