Firstly, thank-you for wanting payback rather than whining that it’s not fair.
I’ve not had a crack at the roaming Triglavians, only at the Emerging Conduits, where you get waves of the Triglavian Frigates and Destroyers - and they are tough. But I am an Amarrian pilot.
As others have said, a Battlecruiser or Battleship with pulse lasers. I’d be inclined to start with a Harbinger with heavy or focused pulse lasers, and a Webifier… put a high resistance active tank on it. If that struggles then then a Pulse Apocalypse is the step up.
Both should do you service as security mission ships as well - so they are not a complete loss. Take some salvage drones with you - Triglavian loot does have a value.