I've read that phrase in a lot of stories and in a lot of different form; could you tell me the official form of that phrase (or maybe idiom) and its meaning?
The common word is 掌握 (hold in one's palm) meaning " have possession and control of something"
掌握軍國大權 (hold control of the government and the armed force)
掌握有力證據 (holding/ have possession of powerful evidence)
There's also an idiom 玩弄於股掌之上 (to toy with someone on one's thighs and palms)- meaning: " play someone like a fiddle"
Another idiom mentioned "in the palm" is "掌上明珠" (pearl in one's palm). It means " treasured daughter"