Would a meteor hammer be a good back up weapon in combat? Would it work against sentient creatures like centaurs or dragons (think httyd size, but sentient)?
In spite of the impressive sounding name, a meteor hammer is just putting your pet rock on a leash and engaging in flagrant mineral cruelty.
Okay, that’s not completely fair. A meteor hammer is a weight (usually metal) attached to a length of rope. (The exact length is based on the user’s size.) In some cases, a second weight is added to the opposite end and both will kept in motion by the user. It is one of the eighteen traditional weapons in Shaolin (using a soft rope and a copper or iron weight. The soft rope is to reduce the risk of self-injury while practicing with the weapon.)
The basic design idea is fairly primitive, but the resulting weapon is remarkably sophisticated. Using it safely is significantly more difficult than you may expect. You need to keep the hammer constantly in motion. In the process of striking, you will bring the weight back towards you, and at that point you will need to redirect it. This is a weapon that requires the user’s entire body to attack. Launching the weight can be assisted from the knees or feet, and both hands are involved in controlling the path of the hammer.
Once the mass moving, it is remarkably effective on contact, however, because the meteor hammer is a “soft” weapon, there is a real danger that it will strike an unprepared user.
Answering the question, “is the meteor hammer a good weapon?” hinges on one factor, “do you know how to use it? ” It can be quite effective in the hands of a skilled practitioner. However, it is also an extraordinarily difficult weapon to master. Following the traditional training pattern from Shaolin, it is the last weapon a martial artist will train with, and use of the weapon assumes staff training, seven section staff training, and rope dart draining. If you can use it, I’m sure you can make it work for you. However, if you simply pick it up and swing it around like an improvised flail, it will be a very limited weapon.
This leads to the specific cases you were asking about. Could a meteor hammer be useful a centaur? Maybe? I’m not entirely sure, but there is some potential. A skilled practitioner can get surprising reach out of their hammer, and if the centaur is unarmored, that could inflict some serious harm to them.
As for dragons? I’m just going to say, “no.” Or at least, almost certainly not. Most dragons (in myth and fantasy) have some kind of protective shell. Throwing rocks at them is rarely an effective strategy, and getting into melee with one isn’t a particularly good idea either (most of the time.)
A minor nitpick, but most animals (including the dragons in How to Train Your Dragon) are sentient. That just means they’re aware of their surroundings, and able to respond to them. You’re probably looking for, “sapient,” meaning the being is also self-aware, and capable of thought (whether it can, or chooses to communicate is irrelevant.)
So, is the meteor hammer a good weapon? It depends on the user. It is a difficult weapon to use. In almost all situations, someone skilled with the meteor hammer would have better weapon options available, and the training to use them. If nothing else, a staff or spear would probably be a much better choice.
The only real exception here is if the meteor hammer was the only weapon available, and the character had extensive training with it. Which is, slightly contrived, but it is the kind of thing you’ll see in the wandering martial arts master subgenre.
Is the meteor hammer the right weapon for your story? It’s a little more complicated. Most weapons are relatively easy to write. They exist in fixed states until a character uses them. So, a sword is in its sheath and remains there, until a character draws it. At that point the sword is in a fixed state of being held. You don’t have to worry about how the sword can move, of the sword doing something unexpected, it remains in a fixed state until your character uses it.
This is not true for the meteor hammer. Readying it will require constant motion and attention from the user. If your character draws a sword, or a gun, they can simply hold it, and be ready for combat, however a martial artist who pulls out a meteor hammer will be engaging in constant activity, even while they’re not taking any other actions. If you’re writing this, you need to understand what those actions will look and feel like.
The meteor hammer is real, but it is a weapon that requires a great deal of skill, both from its users, and from any writer that wishes to use it (in prose.) While it is a good weapon, and beautiful in demonstration, it may not be the right weapon for your story, and that’s a more important consideration.