1.u can max (almost) all ur skills no matter u r 4th job or not.
that means u can max (almost) all ur current job skill while clicking the NPC.
2. It doesn't max ALL 4th job skill. My shadower has no Shadow Shifter and Venomous Stab skills.
GM please fix this bug. Or at least make an option to undo what the NPC had done to my characters.