I recently re-armed my FDL.
It was
1x C4 Overcharged Autoloader Multicannon
2x C2 Overcharged Autoloader Multicannons
2x C2 Efficient Burst Lasers, one with Scramble Spectrum and one with Phase Sequence
I re-worked it by changing the C4 MC to Corrosive and swapped the burst lasers for Efficient Thermal Vent Beams. Better against shields of course, runs much cooler and the corrosive does a better job against the hull of course.
Scramble Spectrum and Phase Sequence may be good mods but the effect in my build was small. Phasing Sequence may have done 2 or 3% hull damage before the shields fall (depends on target of course). Scramble Spectrum I couldn't tell what was affected. I'm sure it's there somewhere but I didn't see it.
The new setup eats shields far faster, and the corrosive means hulls go faster too. Happy with the new configuration. It's not as exotic, but kills ships faster. Good enough for me.