AUW stands for All Up Weight. The acronym of the day which stands for the total weight of an rc aircraft.
For real gliders, according to this site:
All-up flying weight is the weight of the Pilot plus all the equipment including the glider. The best way to find it is to stand on the scales dressed in all your flying clothing, boots etc. and carrying your glider bag with all the equipment you take flying with you. If this is not possible, you can obtain a rough approximation by adding 15 to 20 kg to your bodyweight – 20 kg if your equipment is heavy, including reserve, back protection etc.; 15 kg if you have relatively lightweight equipment. To calculate your bodyweight in kg if you know it in stones and pounds: