Yep loremaster is one of my solutions for this right now. In Arena mode character sheet should not only display character stats and talents, but also their memorized skills. Also allow the full sheet to be displayed without the requirement of points in loremaster (only in Arena of course). This should greatly reduce the advantage of sneaky disguise.
As for broken builds, well that's why we need to allow custom builds ASAP. Larian should see how far people can push things before they decide on what's broken and what's not.
