Ghost Killer Weapon Fusion
(from Starfinder Core Rulebook)
Attacks from a weapon with this fusion deal full damage to incorporeal creatures. They also pass into the Ethereal Plane, allowing such attacks to affect ethereal creatures normally. Weapons with the ghost killer fusion can also score critical hits against incorporeal creatures. In addition, an incorporeal creature (though not an ethereal one) can pick up, move, or wield a ghost killer weapon.