Maybe have a "tholian web" type of weapon. If your vessels are within 1, 2 km of each other there is a laser weapon connecting the special type of ship or the ship with this weapon type. Any opposing vessel passing through the line will suffer damage.
Damage would increase as the level of the weapon or the ship goes up. Maybe distance too.
I think of it mostly as an anti wing/squadron weapon / anti spawned vessel weapon.
There are some types of spawned vessels that circle their target. Some vessels get in the middle of formations an are subsequently inside of the firing arcs.
Several alien bases already have this concept in static positions.
As for the actual game mechanic, maybe its a two part system. Each ship has to have a special to use this concept, so a special slot, and then they have to have a laser weapon in one of the weapon slots.
If done this way the Tier doesn't really matter. Make the special a percent of the ship mass. And in theory any tier could use it.
The drawback is the laser weapon has no normal range because it can only connect to another ship with the special. The other drawback at least two vessels refit time and special and weapon slot used up.
You could enhance the Special with Plasma, or the other elements.
The other option would be to have a special type of ship that does nothing but this. Say you are in the Rampart formation. The vessel in the center could have this feature and connect to the other ships surrounding it. If it is a ship with this ability, then I suggest a longer range 2 or 3 kms. And maybe it increases as the ship moves up to Elite. Adding a km at 2, 4, and elite, for a max of 6 kms.
If its a vessel maybe have this only work with this fit in a Squadron slot instead of a weapon slot. Essentially force the player to install say a Mercury Beam or equivalent to get this ability.
Anyhow Something to think about, tinker with.
Thanks for reading this.