Weapon differentiation - possibly a replacement of the old D&D “damage vs. small / damage vs. large” system currently in use. Weapons would do the same damage regardless of what size the target is, but might get a damage bonus or penalty based on if the target is vulnerable or resistant to piercing, slashing, or whacking/blunt weapons. Being resistant to this weapon type means that the damage is halved; being vulnerable to it means that the damage is multiplied by 1.5. Some obvious examples:

• Most undead are resistant to piercing damage. Skeletons are additionally vulnerable to blunt damage.
• Thick-hided animals are resistant to slashing damage.
• “Blunt is best against hard things, slashing is best against soft things, piercing is best against fleshy things”