You can view the attachments by going to multiplayer on the main menu, choosing "My Career", pressing  twice to get to the "Weapons" sub heading.

Here you will see all weapons and their attachments spilt into five sections, which are:

• Scout Weapons - Scout class exclusive weapons
• Assault Weapons - Assault class exclusive weapons
• Support Weapons - Support class exclusive weapons
• Insurgent Weapons - DLC Class. Don't worry, the few pistols that appear here unlock as you unlock other classes.
• Shared Weapons - Weapons that all classes have

If you choose a weapon, it will tell you the requirements of every attachment for that weapon. There are too many requirements for me to list here so just look at them carefully, so that you will have a fair idea of what you need to aim for. You not NOT need to unlock the explosives for this trophy.

When you are in a match, you can see what you need to do to unlock each attachment on the loadout section of the spawn screen, you could also go to the  Killzone Shadowfall Website, log into your account to view the requirements and your progress as you play. You can get this this trophy from playing multiplayer normally but if you want the trophy quickly or need this specifically, refer to below.
 

Weapons Bot Boosting Guide

Go to multiplayer on the main menu and choose "Create your War zone". You can now choose whichever maps you prefer, the Penthouse and the Forest maps are recommended because of how small they are. You then choose whichever game mode you prefer, either Deathmatch because it's about killing specifically or Beacon Safeguard because you know where the enemies will be are recommended. Set the "Time imit" and "Points limit" to something high if you plan to boost for a while.

(OPTIONAL) To make things easier, you can go to the "Abilities" sub heading and disable the following:

1. Emergency Teleport - Bots could teleport away from you when you're trying to kill them.
2. Turret - Very overpowered, you don't want it stopping your weapon kills.
3. Drone Buddy - You want the kills yourself, you don't want drones stealing them or shooting at you either.
4. Guard Drone - Get this out of the way too.

Now go to the "Bots" sub heading and change "Bot count" to 11 and "Bot difficulty" to Easy. Finally go to the "Settings" sub heading and change "Spawn timer" to 1 second, "Ammo settings" to High and "Pregame wait time" to Off.

(OPTIONAL) To make things even easier, you could in the "Settings" sub heading and change "Health" to Low and "Health regeneration" to slow.

Once you have this done, you have to press  and name your war zone. Once this is done, you will be redirected to the "Browse War zones" section. Press  to go to "My War zones" and then join your newly created war zone. Now you must play with the bots and try to reach every attachment requirements, this could take some time but the bots should be easy to dominate when set to the easy bot difficulty. If you have any questions about weapon boosting or any more tips, leave a comment on the guide and I will reply and put it in the guide.

Notice regarding server closure

A tweet confirming server closure has been issued, rendering the multiplayer trophies and platinum trophy (if online hadn't been done yet) unattainable.

"On 12 August 2022, online servers for Killzone: Mercenary, Killzone Shadow Fall (including Intercept Mode) and RIGS: Mechanized Combat League will shut down. Online features (including online multiplayer modes) will cease on that date. Single player offline modes remain available."