Whenever we imagine medieval battles we often think of knights and soldiers charging into battle while brandishing their sword and shield. The sword and shield became so well known that people started to look at it as being cliché, and started to think that other more exotic weapons, like chains, maces, and two handed axes were more potent in battle. But the truth is, a sword and shield, in terms of offensive and defensive potency, cannot be beat. There are other weapon combinations that might have more offense or more defense than a sword, but none that have the same powerful combination of both.
Within the standard sword shield combination, the sword acts as both an offensive and defensive weapon, slashing at the enemy while also having the capacity to parry oncoming attacks. The shield is mostly used for defense, and a strong shield combined with a smart wielder can block even the most powerful bludgeoning attack (which would have an advantage over a sword alone). The shield can also be used for offense, as the sword parries an attack from the opponent, the wielder can use the shield to bash or push the opponent backwards. Because of this, the sword and shield, while standard and cliché, is near unbeatable in melee combat to this day.