Vigilance has a number of good fits. Its actually a really good frigate. First off its fast, only the wolf, tempest, and kite are faster(ignoring other phase ships, TT brawler with active, and SO ships) so its not going to get caught.
It has low dissipation but it does have an omni shield and its medium mount is on a turret, which means that its much more effective than normal.
Good options for the energy slot are
Graviton Beam/Ion Beam/Phase Lance
Good options for the launcher are
Salamander Pod, Harpoon Pod, Sabot Pod
The Salamander option is pure support. But it does it really well. Most efficient Salamander per DP so the Graviton/Ion beam harass is just icing
Sabot Pod lets is duel other frigates pretty well though the AI isn't that good with this a pulse laser or phase lance will do plenty of damage. Harpoon lets you dump on things.
I prefer the Gravoton/Ion/Salamander option. (you can actually get Salamander, Graviton, vents to keep shields up and fire the graviton with no flux increase, max caps, eccm, and hardened subsystems without the OP skill)