Quoting Kongdej, reply 13I just like how you cast spells quicker, and crit more often with your spells, if you have a dagger in your hand...
I do believe Derek posted something about looking on the magic immunity of the obsidian golems though, but don't take my word for it.
~ K
Are you serious ? I mean, it's nonsense to run faster and cast spells faster if you have a dagger in hand, rather than a club or .. nothing !
Maybe it makes your champion feel more secure knowing they have a good blade in their hand. The added confidence makes them hesitate less and therefore move quicker and cast spells faster.
It doesn't really matter, IMO; daggers do +inititative, that's their bonus in the game. Swords, Axes, Spears, Clubs all have their distinct bonuses and drawbacks.