"The promise of a lord was worth its weight in gold"
Well... promises don't have eight comrade so it's worth absolutely nothing. I guess one could consider the weight of the air in the lord's lungs. An average ***** breathes in about .5 liters of air, 1 liter of air weighs 1.293 kg, so the promise is worth approximately .6415 kg of gold (note these numbers are taken from Google so take it with a grain of salt)
SleepingWolf