Hi,
Its a size 10 weapon, to be mounted on your ship, that is "SPECIAL" category.
It provides 30 Attack for all forms of attacks, except for when u do planetary invasions (Invading other planets), then it becomes twice as powerful = 60.
Text of wpn reads: "Provides 30 attack power, but is twice as deadly when performing planetary invasions."
Its a worthy weapon IMO as even at Heavy Plasma Canons (Lvl 5 adv weapons plus various lvls) yield +52 at size 19. The upkeep is a bit hefty though, at 10k/day, but i guess its worth it.
It is also like most other unique tier rewards (rewards u get when u finished X nos of missions), sellable - i.e. u can sell it..... IMO, all tier rewards should not be sold however.
Do check out the birthing wiki painfully put together by some good ppl.