It wasn't JUST because he does or does not sneak. It's that combined with your choice of light armor, dual swords, and the fact that you implied he is more aggressive. A stealthy guy with light armor and twin blades is a rogue. If he just charges in with the same gear it more fits a barbarian style.
Right, I probably gave off the wrong impression. The furthest thing from this style would be a Barbarian. When I think of a Barb I think: Heavy, Smelly, Clunky, Forceful..this is all about finesse, fluidity and elegance. Someone like this would be a very sophisticated member of society and perhaps have an enormous wealth as well as a hunger for the finer pleasures of life, but could eviscerate and dispatch a true barbarian with a simple pivot and flick of the wrist. I hate to make this comparison but think sort of a ...Reaver (Fable) or even Mercer Frey. Thieving and murdering isn't out of the option, but this is more of a traditional duelist type. Even somewhat of a zealot in terms of their battle prowess.