I honestly haven't messed with the advanced editor in the last few months, but there are two ways you can do this, I believe.
Firstly, you can go to the script of the page you are wanting this to appear on and input:
IF %STAT <= 15 THEN $PAGETEXT := $PAGETEXT + "warrior."
IF %STAT > 15 THEN
IF %STAT <= 21 THEN $PAGETEXT := $PAGETEXT + "wizard."
IF %STAT > 21 THEN
IF %STAT <= 29 THEN $PAGETEXT := $PAGETEXT + "Assassin."
Alternatively, you can use both scripts and on-screen to give you a little more control. Go to the link script that leads to the page on which you get your report card and input:
IF %STAT <= 15 THEN %CLASS := 1
IF %STAT > 15 THEN
IF %STAT <= 21 THEN %CLASS := 2
IF %STAT > 21 THEN
IF %STAT <= 29 THEN %CLASS :=3
Then, on the actual page where you get the report card, insert:
%%CLASS%=%1%Warrior%%%%CLASS%=%2%Wizard%%%%CLASS%=%3%Assassin%%
The latter method will allow you to have text after the declaration of the player's class.