手裡劍

straight or circular throwing-knife used by ninja and samurai (loanword from Japanese 手裏剣 shuriken)

hand / (formal) to hold / person engaged in certain types of work / person skilled in certain types of work / personal(ly) / convenient / classifier for skill / CL:雙|双[shuang1],隻|只[zhi1]

lining / interior / inside / internal / also written 裏|里[li3]

in hand / (a situation is) in sb's hands

double-edged sword / CL:口[kou3],把[ba3] / classifier for blows of a sword