Ok , we'll do it another way then.
First do what you already did - switch the classes , so the paladin is below like this :
heroclasses {
0=warrior
1=mage
2=paladin
leave everything else like it was in the original hero.txt file.
Then in the ses.kfs there is a file called logic_hero.lua , replace it with the file located in the archive that I uploaded in this message. Now you'll start with paladin's army and params and also level up runes and leadership accordingly. Just copy your original ses.kfs anywhere for safe keeping
