Balancing Main-hand weapons and Off-hand weapons

First of all, what are main-hand weapons?

Mainhand weapons are the one that uses left click to use it like sword, axe, and trident. (also pickaxe, shovel and hoe)

Offhand weapons are the other weapons that can be used by right-click, such as shield, bow, crossbow, and also throwing trident(both loyalty and riptide).

When balancing those weapons, I think it is balancing among those two categories is better than balancing at each weapon individually.

For example, having good sword/axe overpowering shield or bow is fine, but flamed punch II arrows 

shouldn't overpower thrown enchanted trident or crossbow.

Also special cases when using both hands to use one weapons like Firework crossbow, it should potentially be as strong as two weapons combined.