The bigger they are, the harder they are to kill. At least for most. But your hero knows how to find the weak points in massive creatures. Your hero does +1d6 damage when attacking creatures three sizes or more larger than himself. An ogre (Size +3) with this ability, for example, gains the bonus only against creatures of Size +6 or greater. A human Giant Killer (Size 0), can claim the bonus against the ogre, however.

Savage Worlds Deluxe Edition p. 38