Sylvius the Mad wrote...
I'd much rather define Warriors as people who specialise in combat, and use combat to solve problems, while Rogues are more likely to use non-combat skills and guile to solve problems. Even Rogue-specific combat skills involve exploiting weaknesses (backstabbing) rather than simply overpowering strength with greater strength.
And I still maintain that Rogues should be less good at combat than Warriors, but Warriors should be less good at nearly everything other than combat compared to Rogues.
Which would be an incredibly appealing answer if,
a) Bioware hadn't decided to make combat a significant focus of the Dragon Age series, including major conflict resolution

The non-combat gameplay and storyline was as in-depth, challenging and rewarding as the combat version, or couldn't be 'covered' by always bringing one rogue in the party.
In terms of combat balancing, its one of the areas where I broadly agree with the Bioware dev (Epler or Laidlaw, if memory serves) who said that one of DA:O's challenges was that damage-dealing rogues and warriors overlapped too much.
In twin weapon / 2H terms, the warrior tended to have the benefit of heavier armour and better group buffs (although warrior tanks also had these, so their usefulness was slightly questionable). The rogue had the advantage of significantly more effective damage-dealing and far better threat management, but if specced right could also take heavier armour if they counteracted the stamina penalty in another way. Twin weapon rogues were incredibly flexible and effective compared to 2H warriors or twin weapon warriors.
Again with archers, rogues got the slightly better deal although both archery lines were somewhat lacklustre prior to Awakening.
DA2 did, at least, better define and balance the benefits and weaknesses of the damage-dealing rogue and warrior roles. But it did so by making both of them combat gods, able to wipe out wave after wave of mindless enemy spawns. I too would have preferred a slightly different answer...but them's the breaks.