There are multiple sets that boost spell critical, already the easiest of the two crit stats to boost, while there is only one that boosts weapon crit? The Night Mother's Gaze set would make alot of sense to have increased weapon crit on, since the first set ability lowers armor, but no it has spell crit.
Not to mention that if you dual wield increased crit chance weapons you rarely get the full bonus, had two weapons of 3%, got 5%.
//And to boot, is the dagger crit fixed yet from the dual wield skill line?