By now there's a couple weapons with unique visual effects- the Devidian Retro phasers, which also feature on the C-store TOS Connie, and the Quad Phaser Cannons from the Sao Paulo. They're both pretty cool, but one of the current issues that come up is that, for the quad cannons you can only mount one, and having any other cannons ruins the effect. For the blue TOS phasers, ultimately they're not competitive with the other end game weaponry- although certainly fun to mount, this is a point where mechanics sort of sticks a thorn into the leg of looking awesome.
Recently I had an idea that I thought would benefit from sharing with the community- and hopefully the VFX devteam, so here it is. (although it's actually two ideas)
1. Give unique weapons a "Disable other graphics" option. If you have a defiant with two dual heavy cannons and your single allowed quad cannon, you can press a button and now only your quad cannons show firing. The cool effect of having quads is preserved without the need to mount multiples (which would also have problems, due to firing timing), and it wouldn't majorly affect gameplay like PVP with invisible shots.
This would also, presumably, work for the retro phaser.
2. Probably less practical but more rewarding: Have unique weapons, or possibly even ships or C-store consoles unlock 'ship costumes' that enable special weapon graphics or the like. A 'TOS' Skin that unlocks TOS phaser and torpedo effects (Maybe even retro cannon effects modeled off the retro phasers). Having the Sao Paulo unlock a costume effect for quad phasers (or just quad cannons, although less likely )
I'd find it nicer if instead a weapon acted like a costume.
EG if you have quad cannons equipped, then by default any DC or DHC works with an appropriate quad-fire animation like the quads themselves, and this can be disabled with the same "disable visuals" modifier seen on set pieces.