Orc weapons are big, crude and not very sharp… much like the creatures that wield them!
During a turn in which it charged, a model with this special rule may re-roll any rolls To Wound of a natural 1, and improves the Armour Piercing characteristic of its weapon(s) by 1.
Note that this special rule only applies to non-magical weapons and does not apply to a model’s mount (should it have one). If the model is using a magic weapon, this special rule ceases to apply.