[baalzy]

Backstab IS what gives rogues their great DPS. Warriors / Monks can get weapon combos that are just as effective as the melee combos of a rogue (monks even better cause of ridic 2hbs). Rangers also have just as good weapon combos (tho a lower cap on melee skills, for now). So pure melee damage in an ideal situation to deal DPS is going to be pretty even between Rogue/Warrior/Monk. It's the 'extra' things they can do which changes their ranking in the DPS charts. Flying Kick for Monk is ultimately what gives them the advantage over a Warrior, because it vastly out damages kick. Backstab is what ultimately gives the Rogue an advantage over a Monk. For a ranger they'd need to be using their DoTs/Nukes/Bow in a smart manner in order to out damage a warrior (at least until velious lands and they get Call of Fire to give them extra DD procs, assuming they don't pull agro and die).

So, that said, focusing on maxing out your backstabs is what will give the best DPS and from the sounds of that the only thing which will boost your backstab damage is having a higher base DMG weapon. If you can't get your hands on a ragefire then go with a rapier of orin or a Serpent's Tooth.

You could also go with a 1hb or 1hs in your main hand and hot swap in an Efreeti War spear (15/40) or Crystalline spear (13/30) to backstab with. I'm not entirely sure how the delay on them affects backstab though.

Of course, as others have said, by the time you're high enough level for anyone to notice the difference you should have a ragebringer.