Three wrong answers in a row.
The piece of cake way is what was done with the Jedi Fighters, constraint "HasPhaseMissiles" and constraint "HasEnergyWeapons" both work just like any other ApplyBuffToTargetsLinked. You give them that constraint, and the ability will only filter down to the specific fighters fitting the filter.
If the constraints aren't an option(you need energy damage types on the others and can't use phase missiles), the more complicated method is by using OnWeaponFired to get a particular buff applied on a particular fighter. You just use the buff checking system I used for slave circuits and a few others and your ability will filter down to the proper targets. The overload is a little higher, but with proper nesting and termination it will function with high efficiency as either an active or a passive.
If you can't use different weapon types either, my well be dry.