"Piercing" on its own means an attack can go through units.
For example, Kongou (from Samurai) has a piercing effect and has an attack range of 3 panels forward in a straight line.
Having a piercing effect means the attack will hit the units behind the first unit that gets hit.
You can also notice that Spear Users have a normal attack with a 2 panel range, and attacking a unit with another unit behind them will consequently hit the latter as well.
To provide contrast, notice how missile units or "gun users" have attacks that can target a unit behind another unit, but if you choose to attack them, the unit in front gets damaged instead, this is due to the lack of a "piercing" effect.
"Pierce" while standalone refers to an attack type from spear users and abilities.
Pierce with an added prefix-like term such as "Defense Pierce, Magic Attack Res Pierce, Spr Pierce" means that a certain amount from the quantitative value of any of these stats is cut or reduced before the damage is calculated.
anoymous
Spear attack
anoymous
It's where people put holes in themselves just to 'look good' (or think they do).
Oh wait, you mean in WOTV? It's damage from spears = pierce, guns/bows = missle, magic spells = magic, bladed weapons/axes = slash.