ezo
Hero
They balanced it by making it a bonus action to attack with a second weapon.don't care how they will balance that but it must be done.
So, apparently you do care how they balanced it?

At the simplest level, you have four options (let us say):
d8 + shield (4.5 dmg, +2 AC)
2d6 (7 dmg)
d8 + d6 (8 dmg)
d8 ranged (4.5 dmg, "but at a safe distance?")
The higher damage, and two chances to hit instead of one, is why the bonus action is the requirement. Could they have done it differently? Sure.
I think attacking with two weapons should be: +1 to attack roll, roll both damage dice and use the higher roll.
This way you get a slightly higher damage average than just the d8 (d8+d6 averages 5.23 taking the higher roll), but the +1 to attacks makes this average slightly higher still. It is almost a +1 to attack, +1 to damage.
I don't know if it would continue to work with fighting styles and feats factored in, but further discussion is best left for another thread IMO.