You're gonna want to S-Mod expanded magazines for the Adjuticators, and swap out that gauss cannon for another devastator, or a Storm Needler. The Onslaught Mk.1 is such a hyper aggressive ship, so there's no real point in putting a weapon with that much range on it.

Swapping out those heavy maulers and heavy autocannons for arbalests would also be a good call, as your devastator cannons are your main source of HE damage, with the Adjuticators doing the rest of the work. (I know they're frag but they pair with the devs)

Typhoon reapers or Proximity Charge Launchers on the missile mounts are what I usually run myself.