Great colors and amazing that there's so little information on the ballband. You can get a better idea of weight if you estimate the number of wraps per inch. Take one of the yarns and wrap it around and around a ruler or a large knitting needle (diameter doesn't matter) so that the wraps touch each other. You don't need a special tool for this. Now count the number of wraps in a given length and calculate the wraps per inch. This table gives some conversions to yarn weight.