If you ask Fairwheelbikes. EE Brakes that has a strange brake that should be very good have also come up with some different brake pad holders:
Without any screw holding the Shimanostandard pads they save weight. And with a different end and without the thing that goes down a little from the holder on mostly of the pad holders. Many small things they save weight with. Ending at low 12,5g for a pair. But at a price at $110
Tune that should be extremely light with their carbonfibre holders is at 13g/pair. AX-Lightness at 14g/pair and normal Sram Red at 19g/pair.
So then you can think that EE brakes has the lightest but they have a competitor. B-T-P:
Not like Tune that comes with both alu- and ti-bolts B-T-P comes with titanium on the front and alu on the rear. For a set for front and rear they are 25g. Easy to count that they then are 12,5g/pair that is exactly like EE. The price from B-T-P is 129€ including pads and then for 2 pairs I hope. Or I read it wrong. See here: B-T-P