Slashing weapon can be found near cave entrance if not equipped.
Look for the sparkling ones which will hold the gems that are needed. Graphical settings need to be at high to see the sparklings. According to the new RuneScape client, sparklings can be seen with minimal settings, too.
Players with level 80 (boosts may be used, must be visible) can mine a crack in the room below the quicksand for 20,000 experience and access a secret treasure room, which contains a Scabaras mask and a Was (sceptre). To reach the fissure room, go down the well (north-west of the Kalphite Lair, fairy ring BIQ) and go in the tunnel in the east wall of the Kalphite nursery. Then go through the tunnel all the way to the other side and enter. You will find yourself in the room below the quicksand.