After you do the initial quest to start the campaign, you will have to do an Orientation quest where you ride a theme park cart into a tunnel that ends in a room full of gold. Complete this quest. The very next quest you get is Dungeon Maintenance where you will go back into the Orientation mission's tunnel to clear some enemies out. The second room you come to has a sword on the ground on your left, sparkling. Press your interact button to pick it up and die, unlocking this achievement.
If you miss this 1st go, this quest appears to be one of the weekly repeatable ones, so no worry.