Piercing and Blunt Edit
Piercing units deal piercing damage counters when they attack, and these can be negated by piercing armor. Similarly, blunt units deal blunt damage counters when they attack, and these can be negated by blunt armor. There are no mechanical differences between piercing and blunt damage.
Note that although Master Spear has an attack type, its Headshot ability is not affected by armor, so it does not matter which type of damage counter you use. The same is true of attacks dealt by Venomous lizards with the Refined Corrosive Agent upgrade.
When a vector attacks a Maggot or Mosquito, the card that was attacked morphs into an Abomination. When a vector attacks any other unit (including Abominations), it receives a Carrier card attachment.
Reanimated units are both vectors and the original attack type of the units. For example, since Hunters are piercing, a reanimated Hunter would be both vector and piercing.