bludgeon v.

1802, "to hit with a bludgeon (n.)," which is of unknown origin. Related: Bludgeoned; bludgeoning.

"short club, heavy stick with one end thicker than the other," 1730, of unknown origin.

A plausible conjecture connects it with D[utch] blusden, blusten bruise, beat .... The E. word, if from this source may have been introduced as a cant term in the Elizabethan period, along with many other cant terms from the D[utch] which never, or not until much later, emerged in literary use. [Century Dictionary]