12% increased Attack Speed while Dual Wielding
8% increased Cast Speed while Dual Wielding 
5% increased Cast Speed while Dual Wielding
10% increased Attack and Cast Speed if you've used a Movement Skill Recently
30% increased Mana Regeneration if you've used a Movement Skill Recently
+10 to Dexterity and Intelligence 
Dark Arts is a notable passive skill that grants increased attack speed and increased cast speed while dual wielding. It grants increased attack speed, increased cast speed and increased mana regeneration if a movement skill has been used recently. It also grants additional dexterity and intelligence.