Ominous Weapon Fusion
(from Starfinder Core Rulebook)
A weapon with the ominous fusion trails a shadowy haze behind it and moans a menacing dirge in battle. The weapon gains intimidation as a critical hit effect. If the weapon already has a critical hit effect, when you score a critical hit, you can apply either the weapon’s normal critical hit effect or the intimidation effect. A target affected by the intimidation critical hit effect is shaken for 1d4 rounds (Fortitude save negates). A creature that gains the shaken condition from a weapon with the ominous fusion can’t gain that condition again from the same weapon for 24 hours.