Quick answer: Keep a ranged-type Phantom Edge in your inventory. Aim upward at the suspended box; when L Ctrl appears over it, press the key. The box drops and breaks, leaving glowing loot at its landing spot.
What you need
Shooting down a hanging loot box takes the Ranged Shot field ability. Every ranged-type Phantom Edge grants it, including Goldblaze and the Flying Dagger.
You don’t have to equip it. The Goldblaze card spells it out: “Once obtained, it can shoot down certain hanging objects at medium to long range, even when not equipped.”
The region map identifies these locations, and the marker tooltip updates after you acquire a ranged-type Phantom Edge. See the explanation of Missing: Ranged-type Phantom Edge.
How to shoot the box down
Get a few metres from the box with nothing blocking your view of it. Turn the camera toward it and tilt up until the L Ctrl prompt appears on the box.
Press L Ctrl once. Soul fires a Ranged Shot, knocking the box off its hook so it breaks on the ground underneath.
Go to where the box fell, because the loot won’t come to you. It sits there as a glowing pickup, and pressing E collects it.
Example: the hanging box at Blackwater Crew Dock
On Meigu Lake, a loot box dangles from a hook roughly 8 m up among the stilts. It’s beside the folded ladder, about 39 m along the shore from the Blackwater Crew Dock bell. Stand at the bottom of that ladder and point the camera at the stilts.
After falling, the box rests on elevated ground behind the stilts, around 6 m higher than the shore, beyond reach from the beach. A blue glow behind the stilts indicates its landing spot.
Retrace the shoreline beyond the bell, then take the slope at the beach’s far end to reach the raised ground. Continue along the higher shore and climb toward the glow; the full route is about 170 m. The pickup notifications list Polished Twinned Metal + 8 and Polished Forged Metal + 6.
After a rest at a bell, knife-wielding Crew disciples and a netter return to the Blackwater shore, so prepare to fight as you approach.
