A pair of hourglass gauntlets, from Charles VI of France’s armour, late-14thC. The original hasn`t fingers and gold decoration, so this is a simple version of them for SCA and living history fight.
Historically, gauntlets were an important piece of armour, since the hands and arms were particularly vulnerable in hand-to-hand combat. With the rise of easily-reloadable firearms, hand-to-hand combat became less common and so gauntlets lost most of their strategic value.
Some medieval gauntlets had a built-in knuckle duster. When the hand was bunched into a fist the backhand protection becomes pronounced from the fist just above the knuckles, this allowed the user to utilize the gauntlet as a melee weapon while still protecting the hand from damage when punching. However, against an armed combatant the use of this feature would have been risky so it was very unlikely that a gauntlet would have been used in this way when a more suitable weapon was within reach. But if the user had no other means to defend themselves the tactics they would have employed would be to attempt to surprise the opponent with this inconspicuous attack, possibly by dodging and countering, aiming for exposed areas of flesh such as the face or weak areas of armour, such as under the arm or the groin.