Apparently folk don't know how to fit a Legion.
There are innumerable good Legions outfits. Once again, they're sleeping on ion; my favourite uses four xyphos wings, though this is largely AI-banned.
There's also gauss/mauler sniper with bombers or thunders, or mark IX + hephaestus linked + pilums, or some sort of needler + hellbore combo...
Two heavy plus five medium focused forward is basically a reliable Onslaught broadside, less the pulse cannon and instead with fighters. It's really not bad. If the main flux pool seems low to you, then use heavy armour so it can drop the shield without worry. Alt: gauss so it doesn't have to get shot. However, because it does indeed have all these weapon mounts, you do want it shooting the weapons, or you might as well bring two Mora.
I suggest maulers instead of missiles because the AI will waste all your missiles anyway. The gauss+mauler damage profile is agonizing, so the low flux support doesn't matter. If your gauss build can't stay away from the front lines, then use the xyphos on it so the harassers get hardlocked.
Folk seem to like the Legion XIV, so let's do the annihilator version. The AI will a) not close and b) waste all the missiles on the shield, so this is definitely player-only.
Step 1: burn drive up to them and focus your twin storm needlers on their face. When they drop the shield, turn on the annihilators. Congratulations, due to the four xyphos LPCs, it can't shoot at you, so you just sit there until you win. With five annihilators, it will not be long. Also if they do manage to pop a shot off, the rockets will try to block it.
The key is you have eight ion beams but have to pay the flux for zero ion beams = 160 OP worth of vents alone. Not to mention the 96 OP worth of laser gun, at a cost of 60. Yikes.
You're not using any of the small slots, because the xyphos have your PD handled. It's like 8 burst PD lasers, again another 56 OP worth, again at the low low price of 60. They keep firing while you vent and you don't have to pay the flux for these either.
Also they'll body block shots now and again. They don't die, so there's no need for expanded deck crew. You also don't need an ITU. You do want expanded missile racks though.
Alternatively, you can do pilums + storm needler + hephaestus. Firing both guns costs 0.67 flux/damage on shields, 0.69 flux/damage on armour, and given it has both explosive and kinetic, the target can't profit by putting the shield up or down. Especially with the eight xyphos fighters raining on its parade. Contrast mjolnir at 1.25. The mk9 has range, but it also has downtime, unlike both of these guns. Due to the xyphos disabling the PD, the pilums will actually hit sometimes. And you don't have to worry about the AI wasting them.
P.S. Five heavy needlers is an insane amount of shield burst. Pairs nicely with hephaestus. Want HVDs instead for the AI, though, since it has no idea about its own shield behaviour.
P.P.S. Maybe do quad trident instead of double Mora, since it has the OP and you don't have to babysit it to get it to coordinate with itself?
P.P.P.S. For stupidly optimized non-missile damage, use three assault chainguns with two storm needlers. Once they drop the shields against the needlers, just hit 'em with the chainguns to raise their flux and thus their EMP arcs from the xyphos. But then, why would you since the AI can't use this either?