i want to suggest to increase range (and maybe clip size) of the Flak cannon for destroyers. I think if there's a ship class which is intended to protect the own fleet and fighting off smaller ships, it's the destroyer class (in cooperation with tactical cruisers).
But at the moment, tha flak cannon for the Destroyers (Agosta and higher tiers, didn't test the Gora or Dola yet) has only a range of ~ 0,9 km to 1,1 km. Thats most of the time fine to defend yourself. But if you're trying to defend your ally next to you, it's way to less. The time you need to fly over and get the corvette in range, is allready enough time for the corvette to kill your teammate.
Very skilled corvette player know this little fact, and always stay out of this range when engaging destroyers or ships close to destroyers, since they can still attack and fire their goliath torpedo above 1,1 km.
It would also nice to increase the clip size from 4 to .. maybe 8 or 10 shots. A T2 Destroyer can kill a T2 Corvette (Dover) with exactly 4 shots of the Flak Cannon, if all 4 shots hit and the corvette is not using his shield. So it's often a question of perfect aiming and timing to get an advantage out of the Flak cannon.
Sine many players are asking for a Corvette nerf, maybe this would be an alternative change, to make it easier for newbies defending against corvettes or to counter corvettes in general without to nerf them.