Re: Part of the issue here is that the French underestimated the tactical effect of combining.....
"The archers went on a killing spree with knives when the French knights were unhorsed and unable to defend themselves while fallen over on very boggy ground."
Henry's forces also used their mallets to finish off the knights on the ground.
It is said that the "V" sign originated in English/Welsh long bow archers showing their "draw string" fingers to the enemy. The French cut off those two fingers of captured archers. IIRC archery practice was a mandatory Sunday activity.