Heavy and lightweight are obvious but what about welter, bantam and straw?
I've heard welter began as heavy horse jockey but no confirmation.
What say you OG experts? 
1ban·tam
Pronunciation: \?ban-t?m<br>Function: noun
Etymology: Bantam, former residency in Java
Date: 1740
1 : any of numerous small domestic fowls that are often miniatures of members of the standard breeds 2 : a person of diminutive stature and often combative disposition 
what weighs more a pound of feathers or a pound of bricks?
groundfighter2000 - what weighs more a pound of feathers or a pound of bricks?
Probably water.
I think its the WFA weight class that really needs to be covered here.