WeightStone solves one simple problem. If you have scales that show your weight in Stones, Pounds and fractions of pounds then this app is for you. Apple Health allows entry in Kg, Pounds or Stones but if you want to use any of these then you need to manually convert from the fractional amounts to a decimal.
This handy little utility allows you to see your last entered weight and also enter a new one by typing what your scales actually display.