Sap

There are two distinct uses of the word ‘sap’ in medieval settings. The first
(and the one used in PotP) is a simple, small, heavy weapon used to knock a
person over the head (think of a roll of pennies in a sock; that kind of crude
fighting device). The second use of ‘sap’ refers to digging tunnels and/or
using explosives to bypass or breach defensive structures.

See also: help skill sap