For my full pannier setup I use 2x Carradice Super C rear (1.9lbs each) and 2 x Ortleib small roller front bags (1.5lbs each) . The total weight is under 7lbs. Carradice are very light for their size and strength, mainly because they use a simple construction and ultralight stiffening. Ortleib have heavier construction but better waterproofing.
Most panniers are far too heavy.