late 14c., "lacking strength, powerless," from un-(1) "not" + obsolete wieldy, from Old English wielde "active, vigorous," from Proto-Germanic *walth- "have power" (see wield, v.). Meaning "moving ungracefully" is recorded from 1520s; in reference to weapons, "difficult to handle, awkward by virtue of size or shape" it is attested from 1540s. Related: Unwieldiness.