Three-stone weakling
From Wikipedia, stone is defined as a unit：
The stone or stone weight (abbreviation: st.) is an English and
imperial unit of weight or mass now equal to 14 avoirdupois pounds
(6.35029318 kg).
One stone is 14 pounds; Three stone would be 42 pounds.
A weakling is a person or animal that is physically weak and frail.
What does "three-stone weakling" mean? A weak person whose weights 42 pounds?
There is another phrase about three-stone: three-stone ring. Does "three-stone" in this phrase mean 42 pounds too? It is quite heavy!
Best Answer
The term 'three-stone ring' may sound similar to 'three-stone weakling' but they are different.
A 'three stone ring' refers to the number of gems within the ring. Example: A wedding ring that has three diamonds.
The term "three stone weakling" refers to a person who is weak and underweight. 42 pounds is heavy, but not in human weight.
This is from 2005:
Asia has the lowest Average body mass(kg) being 57.7 which is 127.2067 pounds. That is more that 3 times more than 42 pounds.
Link to where screenshot was taken from