you can do that with simple notepad but I recommend Notepad++

https://notepad-plus-plus.org/download/v7.5.6.html

You need to convert some entity files in the GameInfo folder, or download converted files here

http://www.moddb.com/mods/sacrifice-of-angels-2/downloads/convertdata-folders-for-rebellion-modders

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.

eg

TITAN_TECHLOYALIST.entity

CAPITALSHIP_PHASEBATTLESHIP.entity (phase is vasari)

and remember some weapons are listed as abilities in the ships entity

CAPITALSHIP_TECHBATTLESHIP.entity is the KOL

you will need to alter the damage in the ability files inside the GameInfo folder as well

 I got everything to work. Light frigates melt in one volley, perfect! Messing with the other variables has been fun too.

Thanks again for the help.