Sentence:  [T]he stem of a stout young oak or ash tree, into the end of which, where the roots had been rounded off, a quantity of molten lead was poured, making the <WSD>shillelagh</WSD> more formidable in such hands than a sword would have been – much harder to parry, and impossible to break. 
Meaning of the word marked with <WSD> tags:  A wooden (traditionally blackthorn (sloe) wood) club ending with a large knob.