Shrewd
Middle English (in the sense ‘evil in nature or character’): from shrew in the sense ‘evil person or thing’, or as the past participle of obsolete shrew ‘to curse’. The word developed the sense ‘cunning’, and gradually gained a favourable connotation during the 17th century.
wiktionary
c. 1300, Middle English schrewed(“depraved; wicked”, literally “accursed”), from schrewen(“to curse; beshrew”), from schrewe, schrowe, screwe(“evil or wicked person/thing”), from Old English scrēawa(“wicked person”, literally “biter”). Equivalent to shrew + -ed. More at shrew.
The sense of "cunning" developed in early 16th c., gradually gaining a positive connotation by 17th c.
etymonline
shrewd (adj.)
c. 1300, "wicked, evil," from shrewe "wicked man" (see shrew). Compare crabbed from crab (n.), dogged from dog (n.), wicked from witch (n.). The sense of "cunning" is first recorded 1510s. Related: Shrewdly; shrewdness. Strutt's "Sports and Pastimes of the People of England" (1801) has a shrewdness of apes for a company or group of them. Shrewdie "cunning person" is from 1916.
