Greater five-finger discount is an aura available as part of the Members Loyalty Programme and can be purchased from Xuan in Burthorpe, for 14,000 Membership Loyalty Points. This aura increases player's chance to succeed thieving stat random by 5%.
It is activated for one hour and has a recharge time of three hours. Also, as with all auras, if the account using it is logged out while the aura is activated, the timer will continue to run out.
Note: you can only buy this aura when you have the 'Lesser' version, as it is an upgrade. Hence the price is 14,000+5,000 = 19,000 Loyalty points.