How to Get the W-Item in FFVII

Take the Highwind to Midgar and hover over the city. The party will parachute down. Once you're on the ground, head to the next screen and go down the ladder. Search both sides of the intersection in the upper-right section of this screen for two chests containing an Elixir and a Megalixir. Go down the stairs, then take the ladder to the next area.

Head to the left and climb the long ladder to find a chest. Open it for an Aegis Armlet. Return and take the right path. Head left, climb the ladder and continue down the path. Go through the tube, then grab the Elixir and the Starlight Phone from the chests on the next screen. Climb down and enter the tube to find a ladder that leads to the Max Ray. Return to the screen where you found the Starlight Phone and ascend the stairs.

Save your game and head through the tube. Here you will enter a battle with the Turks. Defeat them by using your most powerful summons and the enemy skill Big Guard for defense. Avoid Lightning, Fire and Ice attacks, as these will heal your enemies. The battle will end when you've depleted any one of the Turks' hit points.

After the battle, head south to the next screen. Continue down the tunnel, collecting the Power Source, Guard Source, Mind Source and Magic Source from the chests along the path. At the very end of the tunnel, you'll find the W-Item Materia.