you can do that with simple notepad but I recommend Notepad++
You need to convert some entity files in the GameInfo folder, or download converted files here
Inside the mods folder
...\Documents\My Games\Ironclad Games\Sins of a Solar Empire Rebellion\Mods-Rebellion v1.85
Make a folder named Damage or something, this will be the mods name.
Inside that, Make a GameInfo folder (case sensitive)
place the files you want to alter inside that, change damage values as needed.
CAPITALSHIP_PHASEBATTLESHIP.entity (phase is vasari)
and remember some weapons are listed as abilities in the ships entity
CAPITALSHIP_TECHBATTLESHIP.entity is the KOL
- TXT entityType "CapitalShip" ability:0 "AbilityGaussBlast" ability:1 "AbilityFlakBurst" ability:2 "AbilityAdaptiveShield" ability:3 "AbilityLastStand" ability:4 ""
you will need to alter the damage in the ability files inside the GameInfo folder as well