Ah, ok I read into the spectrum thread a bit more.

It looks like we will be able to get additional rewards as the event moves from Phase to Phase:

Are there any other rewards for completing the event?
► Yes! We have many permanent rewards for this planned. However, to get every reward, you have to play all of it and finish it BEFORE 4.0 goes Live.

But it sounds like we have to finish everything for the ship weapons… Or else maybe it’s just to complete phase 1?

Confront the ruthless pirates terrorizing the Stanton system, defend its people, and (if you complete the whole event before 4.0 goes live) exclusive permanent in-game ship weapons will be yours!