Source: Starfinder Core Rulebook p.162
You know how to use a special weapon.
Prerequisites: Proficiency in basic melee weapons or small arms.
Benefit: You gain proficiency in a single special weapon of your choice. If the special weapon you choose is a melee special weapon, you must have proficiency in basic melee weapons. If the special weapon you choose is a ranged weapon, you must have proficiency in small arms. If a set of special weapons are all different models of the same weapon, proficiency in one such weapon grants proficiency with all weapons in the set.
Normal: You can take this feat multiple times. Each time you do, select a different special weapon.