In most fantasy the most common weapon is the sword. That is perfectly reasonable as it was the most common weapon on a medieval battlefield, but that doesn’t necessarily make them the best or most interesting weapon for all your fantasy stories if for no other reason that they have been used a lot. If you want a weapon that would be used by someone with less money or by a truly aggressive warrior who wanted to do a lot of damage on the battlefield another great option is the axe. And just like swords there are a number of different types of axe and reasons a person might want to carry one.
Unlike a sword an axe is an almost purely offensive weapon. If you are trying to block with an axe you’re going to be at a significant disadvantage. But that isn’t all that important because with a good heavy axe there is little need to be defensive because it’s almost impossible to parry an axe with the sword and even blocking it with a shield is going to be uncomfortable and dangerous.
The danger is because in most cases shields would be wood with some leather and, if you were lucky, metal studs. We all know what an axe does to wood and that isn’t uncommon the battlefield either. But even if the shield is metal or doesn’t break an axe blow hitting a shield is going to hurt and so long as they remain aggressive counterattacks are going to be very difficult. This is a huge advantage for someone with an axe because so long as their opponent is constantly on the defensive they are in little to no danger while a single blow with an axe is likely to end the fight.
For the fantasy writer the primary advantage of the axe is the psychology of it. An axe immediately tells you something about the person or culture who is using it. Anyone using an axe is going to be aggressive and likely not just on the battlefield. The most famous of the axe wielders in history are the Vikings and the most aggressive of them are the berserkers, both of which would make a great starting point for a fantasy race.
But it’s not just going to be the psychology of the people using the axe that is important. In many ways the primary value of the axe is that it is scary. Someone using an axe is likely to be bigger, stronger and more aggressive than almost anyone on the battlefield. In fantasy this effect could be even more impressive if the axe wielder is a troll or giant who is far bigger and stronger and possibly with some more impressive natural defenses making a single enemy or small group a real deciding factor in a battle.
If you truly want to make your axes interesting though you’ll want to make certain they fit the character and what they are used for. Axes come in a wide variety of types. From those used to cut wood on a farm to weapons made specifically for battle. Thinking about this is going to give your weapons far more personality.
In the cases of war axes the primary difference is size. As a weapon they can from a one handed hatchet or tomahawk (including those that can be thrown) to massive war axes. The largest axes used on a battlefield were used by the Saxons. These massive axes were about five foot six feet tall and only the largest warriors would be picked to use them. Weapons like this would be devastating to anyone who got in range of them the bigger they are the more difficult they are to defend against.
In fantasy armor is often overlooked, but if you plan to use armor the axe has some more interesting aspects. That is to say that a well made axe is going to be fairly useful against almost any type of armor. Chain armor is going to be almost useless against an axe because a single blow is going to break bones whether it cuts through the armor or not. Against plate it’s less useful but it can still do more blunt force damage than a sword because more weight is in a smaller area. Also many axes have a spike or smaller blades on one side and an axe blade on the other. This is primarily for use against armor since the spike would go through a helmet or plate better than the blade.
I personally can’t think of a single magical axe in fantasy literature though it was a very common weapon throughout much of the dark ages and a magical axe could have a number of interesting uses. Perhaps a weapon that magically protects the user allowing for even more aggressive use of the axe or one that made them berserk. But even without the use of magical axes there is plenty of room for the use of more axes in fantasy literature and having a few more characters carry one of the most brutal and devastating weapons of the medieval age is likely to add a fair amount to drama to your story especially if the characters personality matches that of the weapon or if you want to add in an entire army of axe wielding men who are an almost unstoppable aggressive force.