Each WoW class has 3 specs. For a rogue, some skills only work with daggers, like backstab, the iconic Rogue weapon. Since the beginning of WoW, Rogues could use maces, swords and daggers. They can't use 2H weapons or Polearms. Blizzard recently added 1H Axes for Rogues. I'm still not sure why, but it's probably due to itemization. If they make a pair of epic 1H axes with agility, then Hunters and Rogues are good to go.
While Daggers and Swords can be various lengths, I always saw the Mace as a kind of "blackjack" (small blunt weapon) used to knock people out. WoW has a "Sap" skill that does just that. I remember the game Thief where you'd have to sneak up and knock people out all the time with a blackjack and drag the guy off.
I agree the Axes are weird, but there is a Rogue spec called "Combat" which focuses more on good old meleeing rather than "Stealth" or poisons and such.
As for weapon speed, the way I understood it was, a slower weapon does more damage per swing, so special attacks end up having bigger "hits". A fast weapon hits more times, but for less damage, so that "burst" of damage will be smaller. So people tend to go for slower weapons for DPS. This applies to all melee classes. Tanks usually go for a faster weapon for holding aggro coupled with passive and active skills.
In WoW's beta, Rogues could use shields (!), now that was weird, but that was taken out before launch.
EDITS: Tired... :\
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