Evidently CCP plan to introduce a new variant of all short-range weaponry, currently called "blighted". They'll be in Phoebe.
(The name is awful. "Blight" is a biological thing and really does not belong in a scifi game, unless you are talking about infection by nanobots or something analogical to the biological. CCP is aware of this from the thread, where everyone is saying "ugh". Hopefully it will change.)
Anyway, "blighted" weapons are supposed to be glass-cannon makers. They are on Sisi right now, although CCP is saying they may change them. On Sisi they exist in the sense that markets know about them (thus you can see their stats). But none are actually available.
Currently they get about 10-20% more DPS than a T2 weapon of their type, and can use T2 ammo. They seem to have T2 power and CPU requirements. Their downside, which is huge, is lowering all ship resistances to 0%. (It's not clear to me exactly how this is supposed to work: is that resistances before or after other modules' effects?) Another downside is (or may be) cost. CCP is saying they will cost like faction weapons. This will depend on how they enter game, though, as well as if they are useful.
In their current incarnation, "blighted" weapons seem pretty useless to me. Highsec gankers might like them, if they are cheap. Maybe a few alpha fits in other spaces. But there is one "blighted" weapon application that does seem useful: torpedoes on stealth bombers. So I am keeping my eye on that.