And when Zopyrus drew an Illyrian short-sword with which to cut off his head, Pyrrhus gave him a terrible look, so that Zopyrus was frightened; his hands trembled, and yet he essayed the deed; but being full of alarm and confusion his blow did not fall true, but along the mouth and chin, so that it was only slowly and with difficulty that he severed the head.
Edition :
Plutarch Lives IX: Demetrius and Antony, Pyrrhus and Caius Marius, Ed. Jeffrey Henderson, trans. Bernadotte Perrin (The Loeb Classical Library 101), Harvard University Press: Cambridge/MA - London 1968 (first ed. 1920).
Remark :
date: The date is taken from the New Pauly.
http://referenceworks.brillonline.com/entries/brill-s-new-pauly/pyrrhus-e1015710