Weapon Expert is a booster that appears in the multiplayer of Uncharted 3: Drake's Deception. It enables the player to add additional MODS to their weapons. It can be purchased from the competitive loadout from rank 45 onwards for $150,000 (in-game currency).
Level 1 enables you to equip two mods on to your pistol. Upgrading to Level 2 requires 8 Gunslinger medals with Weapon Expert equipped. Level 2 enables you to switch your Long Gun and Pistol instantly. Upgrading to Level 3 requires 15 'Triple Threat' medals with Weapon Expert equipped. Level 3 enables you to equip two mods on your long gun.
Weapon Expert has long been frowned upon by people who don't use it due to players rampantly using blindfire and rate of fire mods on their guns.
Before Patch 1.15, players would be able to get 'Triple Threat' medals with ease by playing Team Objective and Plunder, due to the fact that there is no kill limit and games go for a considerably longer time than a Team Deathmatch. Now, Naughty Dog has nerfed many elements in Team Objective and Plunder by removing 'Gunslinger', 'Assassin' and 'Triple Threat' medals among many others.
It is now suggested that to get Triple Threat medals, you are to find both a Long Gun and Pistol which you are comfortable aiming with and use the right loadout as well as the right kickback. A kickback suggested is Quick Boom as well as running Daredevil as your second booster. Getting Daredevil to Level 2 means you can get a grenade once you taunt over an enemy. Doing this while using Quick Boom and a short taunt such as Pump (available to purchase for $100,000) or Kiss (available to purchase for $10,000) means you can get near endless grenades.