Remember: "Though the dagger is still considered a one-handed weapon skill, the perks for the weapon are housed under the stealth banner."
From http://www.gameinformer.com/b/features/archive/2011/01/24/skyrim-building-better-combat.aspx?PostPageIndex=3
It makes a lot of sense too. You don't go to war with a dagger, but you don't sneak around with a claymore or a warhammer.
I am a fan of this division as well. If I've been battling with a sword for 10 years I should be able to take what I know and do roughly the same with an axe or a mace. However, I wouldn't have a chance if I had to use a big, heavy claymore, as I'm not used to the weight or using both hands.
Smart move, Beth, smart move.