In the legal culture, "fairness" is undoubtedly a very important value concept. In order to reflect this idea, both eastern and Western cultures show "fairness" as a certain image of things, making it more intuitive.
In western culture, the symbol of fairness is the Scale. As for why the balance is used to symbolize fairness, its significance is also quite obvious: the Scale can accurately reflect whether the weight of the objects on both sides is equal. From the perspective of "equality", it does reflect the characteristics of fairness.
Therefore, in the image of the "goddess of justice" symbolizing justice in the west, the goddess holds a Scale in one hand to reflect fairness, while holding a sword in the other hand to symbolize the power of safeguarding justice.