Im no smith so take my information with a grain of salt.
I cant say that I have met any rogue blacksmiths though. Off the top of my head, I would say if you had to pick one, go sword smith because PvE swords work better with Sword Spec than maces, and PvP swords/maces are the same (given equal stats). So no real reason to get maces.
Personal Opinion follows, if you dont care dont read: I would pick up a different profession than smithing. Letherworking for DPS and leg armor, and engineering for goggles mainly, but lots of fun gadgets that rogues can utilize well: such as ranged attacks from bombs usable while moving, polymorpher, and jumper cables in PvP that are very useful in combo with vanish.