Matthew Poole and continuators on 1 Samuel 17:51

51 Therefore David ran and stood upon the Philistine, and took his sword , and drew it out of the sheath thereof, and slew him , and cut off his head therewith. And when the Philistines saw their champion was dead, they fled.

Hence it appears, that David was not a little man, as many fancy; but a man of considerable bulk and strength, because he was able to manage a Giant's Sword; which also he did, both here and below, Chap. 21. 9.

Qu. How could this be, when he slew him before with the Stone, v. 50? Answ. There he gives a general account of the Event of the Battel, and of the Giants Death: but here he gives a particular Relation of the manner and instrument of his Death. The Stone threw him down to the Earth, and bereaved him of the use of his Sense and Motion; but there remained some Life in him, (as frequently doth in such cases) which the Sword took away, and so compleated the Work.