Currently I am looking into modifying my own personal balanced Auriel's Bow (most of the people seem to increased the damage too much. Even playing on master the damage is too high).

As I just started on the creation kit, there are few things I am quite confused.

1) is there any way to find a relationship between different entries? e.g. DLC01EnchAurielsBow, DLC01EnchAurielsBowBlessed, DLC1AurielsBow, DLC01EnchAurielsBow. (I can sort of figure out how each related to each other, but I don't understand how do the condition inside DLC01EnchAurielsBow trigger the damage of DLC01EnchAurielsBow. And also what is DLC01EnchAurielsBowBlessed use for)
2) What are the two damage effects inside DLC01EnchAurielsBow and DLC01EnchAurielsBowBlessed mean? Why do we have two?

Thanks in advance for any pointer I can get

You can right click forms in the object window. Right Click > Use Info. This will tell you what that form is getting used by.

I don't have Dawnguard so I can't be super helpful.

What are you finding too overpowered about the Bow?
The raw bow damage? Or the effects it applies to targets?

The bow itself is underpowered as weapon from god. But a lot of people changing it damage value too high

It sounds like you just need to change the "Damage" Field in one or both versions of the bow.

http://www.creationkit.com/Weapon

As a guide you could look at Damage for other bows and see what you think might be an appropriate value.

Hope this helps.

Thanks, yea I know maybe only need to tamper with damage field. But I think while I am at it I may just play around creation kit more to see how it work