Question about Piercing

I apologize if this is written somewhere else, but I wasn’t able to find it. What little I did see about this was for other 2d20 settings.

I I’m trying to figure out how something like Exploit Weakness, which gives an attack Piercing 2, would interact with an attack using a Fighting Knife, which already has Piercing 1.

Would the Piercing stack, resulting in Piercing 3 for the attack. Or does only the better one apply, meaning that it would only be a Piercing 2 attack?

I appreciate any assistance that anyone can provide. Thank you!

Rules as written, the attack “gains the Piercing 2 weapon effect.” If this was meant to stack, it would have been written along the lines of “increasing” the effect.

If you compare the Exploit Weakness talent to All the Best Hiding Spots or Like a Shadow talents (all on the same page), you see that the wording of the rules is pretty clear, when numbers should stack.

Also, stacking bonuses tend to slow down play as they require more bookkeeping. I’d say it’s a design principle of all 2d20 systems to be narrative and fast systems that are not slowed down by crunching numbers.

Thus, I’d argue that Piercing does not stack and the Piercing effect of a Fighting Knife would rather be increased to 2 and not by 2.

It is supposed to stack. Else, if you had a Piercing 3 weapon and it would be replaced by Piercing 2 after an Exploit Weakness, you would make your weapon less effective by going for weak spots.
In other 2d20 RPGs this Piercing 2 quality stacks with whatever Piercing X the weapon in question already had. If the weapon had no Piercing X quality, then it gets Piercing 2 for the first attack, if it had Piercing 1, it now has Piercing 3 for the first attack, etc.

This works the same as in Infinity or Conan with those Piercing X qualities and the Exploit action.