According to the Essentials Red Box rules for leveling up, rogues get the Weapon Finesse class feature at level 2. That gives them +1 to attack and damage with light blades, light crossbows, short bows, and slings.
According to the Thief preview from the WOTC site, Weapon Finesse is granted at level 1. It’s not explained in the preview article. Not sure which source is right.
Also according to that article, a feature called “Improved Weapon Finesse” is granted at level 9. I have a theory about what that feature gives you, and my theory involves the modifier +2.
Go thou and play a level 9 thief!
Interesting! Dagger will probably take a backseat to short sword as the defacto rogue weapon for thieves! Though I suppose trading a range 5/10 weapon for a +1 to weapon damage is a legitimate dilemma.
If Improved Weapon Finesse does give an additional +1 to hit and damage, it will be pretty darn powerful (+2 attack and damage over most other classes!), and I’ll have a lot of respect for the thief class in terms of pure power. Should be interesting to see if that’s the case.