Yes, it is possible.
To find the file, just make a reshearch of a piercable IK.
Then simply modifiy the condition/switch or whatever with adding the IK of baruna.
I'm actually on my phone, that's why I'm not precise.
(this message will be edit later)
EDIT:
_Common\Item.cpp
BOOL CItemElem::IsPierceAble( DWORD dwTargetItemKind3, BOOL bSize )
I think it's enought, just look at this function