I have that exact same thing. It's a Tricobalt Mine Device (or whatever it's called.) I looted mine from the last stage on the Cure, if I recall correctly. I also looted a Borg Medical Analyzer from the ground portion of The Cure.
You can get purple "anti-borg weapons" either from space sections of STFs or from turning in Marks of Valor to one of the ships in Battle group omega. Im pretty sure its 35 marks for a ship or ground weapon
You gain marks of valor from completing the various stages of STFs
I saw a guy the other day who had a very rare quality mine launcher which had a +1000 radiation damage to borg ships. I didn't have a chance to ask him where he got it.
Does anyone know where I can get a weapon like this? thanks!
I have found that if you have all purple weapons on your ship the borg are no match but as far as the tricobalt weapons yes they have very high damage rates but the thing is that they ar even slower than the plasma, you get a good shot off with the torpedo you get lucky and it hits big but they can shot out of the sky quickly and are really no good in PVP and have to timed right in PVE, the mine and the torpedo have slow recoup rates and if you load it on your ship without any other torpedoes then you only have one shot to take, best is to load purple quantums, and the mine doesnt always stay to its target it can sometimes just sit there in space even if it is right in front of your target and they also like other mines can be shot down easly.They have the power but you have to have that lucky shot.