For this trophy you need Legendary (Yellow) equipment in each slot including both bows and both melee weapons.
-Both Ranged slots (You unlock the 2nd slot by getting the Bow Bearer Ability on the Hunter side of the Abilities Tree)
-Both Melee Slots (You unlock the 2nd slot by getting the Weapon Bearer Ability up on the Warrior part of the Abilities Tree)
One of the fastest ways to get Legendary weapons is by killiing phylakes, or completing quests for Reda the wandering child merchant. The Backstore ability, from the Seer tree, will make Legendary mounts available from merchants.