That whole Brandon quest thing for Tenebrium training is really disjointed right after getting to Silverglen. It's just badly/over written.
"Oh hey, want to do something for me? wink wink, nudge nudge"
"Yeah, sure! Let me do something you didn't give me ANY details about."
OR
"Uh, no, not interested in your shadey ****."
Even though it's just ore, that you can get without even having to steal anything (Cart outside of Sacred Stone blacksmith building, absolutely free). It's a huge factor later in the game with a insignificant seeming sidequest introduction.
I agree, it seemed like it was going to be some thief sidequest thing (something against my character concept) - not something vital for the latter areas of the game. A bad flaw in an otherwise good design.