Influx Waver

Swing it and a blue blade flies out. When it connects it blinks to another enemy nearby and does it again, so a single swing can land on three separate things without you tracking any of them. In a crowded room you point it roughly forward and let it clean up.

Martian Madness, the Pillars and any invasion with packed ranks. Against a lone boss the chaining does nothing and you are left with a broadsword throwing one projectile per swing, which is fine but not the reason you kept it. It comes off the Saucer, so if you are farming the event for the other drops you will see one eventually.

Melee speed makes the projectile fly faster but does not make you throw more of them, so speed bonuses do less here than they look like they should. Reforging is the only thing that raises the actual rate of fire.

Hold onto it long after it stops being your main weapon. The Zenith recipe wants it.