Jack Frost nade launcher... for the Firebug.
Seriously though, a firebug napalm launcher sounds like a ton of fun. Make it noticeably weaker than an off-perk m79 (for initial damage), but couple it with burn damage.
Preferably light enough to run Trench gun + Launcher
That way it doesn't do what the flares did and and just be a stronger version of older weapons.
Instead, it does less damage than an m79 until after 3 seconds of burning, and should drop 6-man HoE gorefasts after 5 or so seconds. That doesn't sound too OP. Might be UP actually, considering how flares have some AoE and instakill with headshots.
Well, balancing can be done later.
That, or some kind of assault rifle primary for the firebug.
So far people tend to say they'd like to see unique weapons and so do I. How about something you made up yourself? I liked the previous weapons like the sawbow or flare revolvers.
Is it possible to make a pistol that behaves different depending what perk your using? That might be cool.
Like the sharpshooter gets bullets which penetrate through several bodies while the demo gets explosive rounds, the firebug sets things on fire with it, the support shoots three projectiles at once, the medic can heal with it in a small radius where the bullet hit so that nearby teammates get healed too but does very little damage to zeds and the berserker gets the ability to block things with it.