Arcane blade didn't help you as much as you think.
People have been mourning this mastery since it's death, but in reality, it's pretty ass.
It adds 5% of your ap to your aa, which means that early game, it adds very little damage. With a dorans ring, you do a whopping 1 extra damage. By the time you finish an item, you're probably doing about 5 magic damage, which is going to be reduced by the minion's magic resist.
Meanwhile, the savagery mastery adds 5 true damage to your aa, out doing arcane blade throughout the early game. So really, it's even easier than before to last hit.