Depends of how many mobs at the same time you gonna kill:
1-3 mobs at same time, is better use one handded and use shield to protect you.
8+ mobs at the same time, is better use two handded weapon and make more damage.
This because you can only block two attack per turns, so if you have more than 2 mobs attacking you the rest ignored the shield defense.
https://www.youtube.com/watch?v=DVDfxnA0rio