Quick answer: Defeat the twin-blade Shadow Warden at the top of the pipe ladder near the Waterfall Bridge bell. His crank opens the hatches by two stone consoles in the Valley Sha-Chi Tower, which hold the Reflex Device and a Primal Stone.
Where to get the Sha-Chi Furnace Inspection Crank
In Weeping Creek Valley, begin at the Waterfall Bridge bell and follow the rocky ground beneath the tower for about 60 m. At the base of the tall pipe ladder, a “Space” prompt appears.
Press Space to ascend the roughly 16 m ladder. At the top, a wooden ledge holds a lone Shadow Warden armed with twin blades.
In our run, the first climb went too far past the top, and the Shadow Warden knocked Soul off the ledge, a fall of about 15 m back to the rocks below. Climbing again and stepping straight onto the ledge started the fight properly.
In our run on Pathbreaker, the Shadow Warden was defeated in about 13 seconds, and the crank card appeared on screen as soon as he went down. It goes straight into your inventory; there is nothing to pick up from the ground.
Sha-Chi Furnace Inspection Crank item card
The crank is a “Story Item”. Its card reads: “A grease-stained round crank, slightly warped by unrelenting heat. Small lettering is engraved on the handle: ‘Inspection Port No. 2 Control Console, Lower Level, Sha-Chi Forging Furnace.’”
Where to use the crank: the lower console
At a bell, choose Traverse to reach the Valley Sha-Chi Tower Base bell (see Phantom Blade Zero bells). The console stands about 13 m away on a red-lit wooden deck next to a railing. It is a stone post with a circular socket on its front.
The “E” prompt appears only when you face the socket from directly in front of the post, on its bell-facing side. No prompt appears from beside or behind it.
Use E, and Soul places the crank in the socket and rotates it. Once the small menu shows “Remove” and “Leave”, choose “Leave”.
A few metres from the post, the wall hatch opens to reveal a glowing doorway marked with an “E” prompt. Press E to collect the Reflex Device, a “Support” accessory. Its card reads “Increases the timing windows for Parry and Perfect Dodge by 15%.” and asks “Equip the new Accessory now?”.
Taking the crank back out
Return to the position facing the post, press E once more, and select “Remove”. The crank is withdrawn into your inventory, leaving the socket empty.
The upper console and the Primal Stone
The same crank also works a second console on the furnace-hall floor of the Valley Sha-Chi Tower, reached from the Valley Sha-Chi Tower 1st Floor bell. It is the same kind of stone post with a round socket, and the “E” prompt shows when you stand right in front of the socket.
Bronze Man: Fist enemies guard that floor. In our run on Pathbreaker, they ended two attempts to reach the console.
Use E to install the crank, then select “Leave”. A hatch opens a few metres from the post; press E at the hatch to collect the Primal Stone.
Taking the stone brings up its “Story Item” card, and then Soul says: “This Primal Stone can suppress Sha-Chi. It really might be able to break the Order’s Mindseal.”
At the post, press E and select “Remove” to retrieve the crank, as you did at the lower console.
