With the advent of the arquebus, and musket accurate rapid fire finally came to the infantry. The ability to train a musket force quickly more than outweighed their expense. As firearms advantages became more apparent to commanders, they were less inclined to take the time to train archers.(the archers of the hundred years war, took decades to hone their skills).
With some notable exceptions, the longbow and crossbow had been replaced . Pike formations, long the "big stick" of European commanders, saw an integration of firearms into their ranks. Imperial musters show that a "Fahlein" or company of 400 men each, started the century with a smattering of musketry in their ranks. By the 1560's pike and gunners ran about 50/50 in composition. By the turn of the century, gunners often outnumbered pike men.
A typical arquebusier can get 4 shots off in a minute. And, given enough ammunition, he can outlast an archer in combat, just in terms of being able to load and fire his piece longer than a man can pull a bow.
With muskets and the new fangled pistols, came an understanding that armor was no longer the cure-all in combat. Although this century saw the ultimate expression in the armorer's art, it did not protect adequately from musketry. A breast and back plate often meant a lead shot penetrated through the front, tearing and forcing open a wound, widening and flattening as it passed through the body, then ricocheting off the back plate. What might be a survivable wound in an unarmored man, became instant death to a man in armor.
"Proofed" or shot-resistant armor made its appearance, but because of prohibitive weight(and cost), allowed only certain body areas to be covered. A proofed helmet and breastplate often weighed as much a a full suit of normal infantry- armor, 40 or 50 pounds.
This change of attitude also shows in the evolution of swords. As armor became less important, swords became lighter, thinner longer. The German rapier is a good example. Less a rapier than a broadsword, it shows the thinking was changing.
Elaborate hilts protected the hand, where gauntlets once were used. Blades changed shape, because they did not have to penetrate armor. Pike formations embraced the "Katzbalger" type short sword, itself a relative of the Roman gladius.(Broadswords could hardly be swung, at "push of pike").
While Claymores and Zweihanders, and specialized pole arms remained as an answer to breaking up pike formations, the average sergeant, officer or noble now carried a rapier, and one or several daggers. Even a pistol or two. Reiters, and Hugenot cavalry were know to carry up to a dozen or more pistols on their mounts; elaborate formations were developed to maximize this new firepower. Rapiers also brought about a new interest in dueling.
Elaborate "schools of fence " developed, embracing any of several styles of fighting. Rapiers were reaching unwieldy lengths; a man who dueled with a rapier often wore a large ruff around his neck, in the latest style. So he was referred to as a "ruffian" Dueling deaths with rapiers became so prevalent among the nobles and affluent of Europe, that Elizabeth I issued an edict that any man entering London with a rapier of more than 30 inch length, should have it shortened, or "cut down to size".
Traditional jousting, long used in warfare, became a spectacle; elaborate armors were developed to protect the participants, and thrill the crowds by "exploding' off a knight. "Knock the chip off my shoulder" is a euphemism derived directly from this.
Artillery also saw a tenfold increase in accuracy, dependability and lethality. Cast bronze guns replaced strapped or welded cannon; standardization of calibers slowly took hold. More guns of less diverse sizes meant simplifying a commander's logistics problems. And the new artillery, the mortar, allowed an explosive to be lobbed OVER an intervening wall, causing causalities inside a fortress.
So all the poor grunt of the period had to look forward to was more ways to die. The Pike still decided the outcome of the battle, but was starting to be superceded by the new toys: firearms.