[Wrana]

As far as I see, description there states "extra damage to lifeless". Such quality is listed only for "Crusherknack", so I don't know for sure. Mod manual states:
#dt_constructonly -
The weapon only affects lifeless beings. All other
creatures are immune.
No other construct-specific qualities.
So you may be right. In which case database description probably needs slight clarification for this weapon type.