Just a quick question
There is no reason why you cant use this power with a thrown dagger and throw it twice on your turn
If you throw a magic dagger, one is enough for both attacks. If you want to get both attacks in melee, you need two daggers.
I think this rule is one of the worst in 4e. While the game isn't supposed to simulate realism, I just can't handle one magic dagger being thrown caught and thrown again all in one power. It's even worst with the blast power where you can actually attack up to 9 foes with one dagger. I make my players have a dagger for each target magical or not.
The reason why the implemented this rule is so someone that uses daggers won't have to invest in multiple magic weapons while someone that uses a bow does not. As a GM, I'll make sure the rogue gets more magical daggers if he likes to throw them around like rice at a wedding.
Who says it has to be caught in the middle? Think ricochet.I just can't handle one magic dagger being thrown caught and thrown again all in one power.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.