In Halo Infinite, you can come across variants of most weapons that you have access to in the game. Dotted throughout the world’s map will be HVT, or High Value Targets, that are Banished enemies that have killed many humans and Spartans in Halo’s lore. Find and kill these HVTs, and you will earn their signature weapon in the armory stations at FOBs, and you can also pick it up from them. Here is where you can get the Unbound Plasma Pistol.
If you are covering side objectives in Halo Infinite before moving on to the main story, this HVT will likely be one of the first things you hit. Their name is Briglard, and they are located at the northernmost point of the bottom left landmass. You can see its location in the screenshot below.
Upon reaching the location, you will see a large gathering of enemies, and The Weapon will note that the HVT is a Grunt, but not to underestimate him. Obviously, a Grunt is not too much to worry about. Just focus on taking out everyone in the area, and you may even accidentally kill the HVT like we did.
Once everyone in the area has died, you will unlock the Unbound Plasma Pistol at any FOB. Just walk up to the armory station and claim it. To test out the weapon immediately, you can pick it up from Briglard’s corpse, or it will be sitting on a nearby podium. When charging up its blast, it will fire a volley of plasma energy instead of the usual charge shot.