From your list, the stem, handlebar & seatpost could all be replaced with lighter ones, and the big one would be the wheels (if you have QR wheels, you have a 9mm axle)

However, the current weigh of you bike is what you would expect for a Alu frame 120mm full suspension bike, and any upgrades to save weight are going to cost a lot of money, unless it's broken, would save that money until you can afford a 2013/2014 bike with at 2x10 (with clutch) drive train, 15mm / 142mm rear axle tubeless wheels & a dropper seatpost, then you will really notice a difference to your current bike; and it will be cheaper long term to buy a complete bike than upgrade part by part a 10 year old bike.

Weight isn't everything, dropper seatpost weigh a lot more than a standard Alu and much more than a carbon one, yet in the few years they have been around, they have become almost standard for trail riders, there control / improved handling is wanted more than the loss of a few grams.