Recently got an S-Modded dun scaith from an invasion fleet, and this is my fit as far as weapons go:
I think weapons are the part you really want help with, so i'm focusing on what my choices were there.
Twin Mjolnirs: while very flux-hungry, they are extremely powerful so with the pretty solid flux stats of the dun scaith it's just about worth it imo.
GH large kinetics behind them for support in taking down shields, any kinetic would work here, even using MK-IX's would be fine imo, i just picked these because they have long range and i know how longer range guns are better for AI usage.
I left the side larges empty because they have awkward arcs, and i decided to focus on frontal damage output.
Rear large is a devastator for optimal fighter deletion.
Medium composites are heavy autocannons because that's all i had available at the time and wanted to be sure i had enough kinetic damage, but making them more missiles might be a good idea to save on flux usage.
For the missile mounts i left the frontal annihilators on there, and (so far) they seem a pretty solid choice, can catch some inbound enemy fire and provide decent HE pressure as well.
The side ones are karions, because that bit of added EMP pressure is nice, but salamanders (as you have) would be a perfectly viable (and lower OP) option.
The front Small ballistics are longish range kinetics, so railguns or any GH/other mod equivalent would work well here, this was just me wanting to be
super sure that i had enough kinetic damage output.
All other small weapons are either vulcans or vulcan equivalent, just to give all around PD coverage where the devastator doesn't reach, i only filled some slots because i was both low on OP, and didn't feel like i needed all of them filled for safe PD levels.
You might want to make your frontal smalls PD rather than kinetic as that will be saner+safer, and also less flux intensive.
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Looking at your loadout, what
I personally would change:
Front most larges from needlers to mjolnirs (or a similar modded weapon)
Next row of larges to use your MK-IX's
Leave the side larges empty
Rear large to a devastator
Front missiles to annihilators (any other HE finishing missile might be a good choice, but annihilators provide other utility as well so i kind of like them in those mounts)
Unsure how much (if any) OP would be left free after these changes, but you could easily just dump it into capacitors, or add flak cannons in the side larges, whatever works for you.
Everything else, i'd have no issue with leaving as-is, Xyphos provide some PD cover and close range EMP
The medium GH railguns are a solid option for those medium mounts, with their long range letting them fire when the guns in the mounts that are further forwards get into range.
You have a decent spread of vulcan coverage.
And salamanders can be very nice to have, so I can't complain about them.
At the very least replace all salamander pods with harpoons, you have enough disabling power with 2 xyphos wings
Xyphos only has 1000 range, so it's not going to be in range of enemies when you're in a long range slugging match, and with how salamanders are engine-seeking, i feel like they fill slightly different roles in the disabling front, Xyphos being short range "general" disablers, while Salamanders are longer ranged engine-focused disablers.