create a mod folder in your mods-diplomacy v1.011 folder, make a folder inside it called gameinfo
copy the frigatepirate*.entity files to the new gameinfo folder, convert the files to text
in EACH of the entity's look for the line 'ExperiencePointsForDestroying' , the number at the end is the experience points
and the line 'MaxHullPoints' affects their hull strength
while the line 'DamagePerBank:' is how hard they hit for that weapon and in that direction.
after altering the file you want to, then load diplomacy go to options click on mods, enable the NEW mod you just created and apply it then test
hope this helps
harpo