Switching classes, please help.

[Conradus]

This is getting me very frustrated with lack of explanation this game offers.

I'm a fresh level 30 Archer (starting class) on my way to become a pugilist. When I confirm that I want to become a pugilist, I'm responded with "you need to complete lvl 10 quest of your starting class before taking another discipline"...

WTF. I'm level 30 atm and my main quest line is sitting at 23 so I already completed lvl 10 quest. I thought maybe I had to complete a lvl 10 guildleve but that wasn't the case. Ugh...

As others said, it's not your main quest line. It's your *class* quest. Every class has its own quest line, handed out at five level intervals at the class's guild. Until you do your level 10 one for your starting class, you can't change classes. I might also note that if the reason you want to become Pugilist is so you can unlock Bard, I'll point out that unlocking Bard not only requires you to be a level 15 PGL, but you'll also have to have done your class quests for ARC through level 30 (which is the last one; you then get job quests for BRD starting at 30 to unlock BRD, and then, once more, every five levels, although they won't all be at the Archers' Guild any more).