Whips are ancient tools that have been around for millennia. They were originally made to direct livestock and later on they were used to punish soldiers, slaves, and criminals. On the surface, a whip would seem like a great weapon for medieval combat. It has a long range, light weight, can be easily used with one hand, and is flexible allowing it to reach past shields. Whips also cannot be parried.
However, there are three good reasons why no warrior brings a whip to a battlefield as their primary weapon.
Unlike every other melee weapon, a whip is useless at point-blank range. A whip only deals damage if it is fully extended and hits with the tip. The rest of the whip isn't damaging and you need a lot of space in order for a full extension to happen. Other big polearms are also unwieldy at targets centimeters away but at least the wielders of those can simply step back or half-hand their weapon and get some good use out of it. No such luck for whip wielders.
Whips has zero penetrating capability. There is a reason why people getting whipped as punishment have their clothes taken off first. Clothing is really good at absorbing the damage done by a whip. Even the lightest and thinnest of armors would block all the damage a whip would do. A person in a coat or heavy jacket would also be immune to whips if they get hit in the torso. Heck, even a t-shirt and overshirt would block most of the pain a whip could deal. If a whip doesn't strike bare skin, it is just an annoying weapon at best instead of a debilitating one.
Whips just aren't efficient ways to kill people. A person can get hit with a whip 50 times and survive. They would be bleeding and in severe pain but they could still easily live. If a person was stabbed with a sword or punctured with a spear 50 times or even a dozen times, they would almost certainly be dead. You need many attacks with a whip to deal lethal damage. Your opponent won't stand still and give you many opportunities to hit them.
In my world, guards of the fountain of youth carry enchanted whips along with shields. These whips are not only reinforced to allow for swinging and disarming but also turn the whips into deadly weapons by electrocuting the targets. Electricity can make the entire non-handle part of the whip deadly, shock people through armor, and be immediately lethal to people. The one new problem would be how to prevent the guards from shocking themselves with the whips? A solution I'm thinking is have the guards be able to turn the electric enchantment on and off like a mental switch. The guards would have to electrify the whips mid-attack and be careful to turn the electricity off before the whip snaps back to them.
So how would an electric whip compare to other medieval weapons like swords, spears, maces, hammers, axes, etc. Would the whips be effective against armored knights wielding typical medieval weapons?