Sentence:  “There the cause of death was soon ascertained ; the victim of this daring outrage had been stabbed to death from ear to ear with a long, sharp instrument, in shape like an antique <WSD>stiletto</WSD>, which […] was subsequently found under the cushions of the hansom. […]” 
Meaning of the word marked with <WSD> tags:  A small, slender knife or dagger-like weapon intended for stabbing.