x1 is a body part of x2 that is meant to dextrously manipulate or grasp objects (along with other potential purposes); x1 is prehensile.
Includes: hands (prehensile), prehensile foot, thumb, fingers, pincers, mandables, prehensile tails, tentacles and/or the suckers thereupon, beaks or snouts (such a prehensile trunks), etc.