The obsidian sword

Hello readers! This week I thought I would share some concept art from my Highmoor book series. For those of you that haven’t read it, this is Joseph, one of the four protagonists, and he’s wielding an obsidian sword that makes its first appearance in the second book. Obviously, this is no ordinary sword; its blade can shatter into dozens of shards connected by an intangible thread, and these shards can be summoned back to reform the blade in the blink of an eye. Fantasy weapons of this type are often referred to as “whip swords” – and today I’ll spend some time exploring their origin and feasibility, before explaining why obsidian is a terrible choice for a sword in real life, but an excellent choice in the context of Highmoor’s magic system.

Whip swords?

I’m aware that Joseph’s obsidian sword is not an entirely original idea. Whip swords are nothing new to fantasy franchises, especially in anime and manga, where creators are caught in an arms race for increasingly awesome weapons. There are dozens of examples of swords that disassemble and reassemble from one blade into a chain of blades, but they are all subtly different. Most whip swords separate into several regular segments, and are presented as mechanical innovations rather than anything mystical. However, there are also examples of swords breaking into clouds of fragments controlled by magnetism or psychic powers. Even Disney introduced a whip sword in Raya and the Last Dragon (2021), so the concept is now comfortably mainstream.

However, no culture on Earth has ever used real whip swords in combat. The closest match is an urumi, from the Indian subcontinent, which is a sword about 1.5 m long, consisting of one or more flexible steel blades that can be flailed like whips. Unlike their fictional counterparts, the urumi “whip sword” doesn’t break into chains of fragments, so it is simpler in principle. Still, it takes incredible skill to use one without injuring yourself, and I’m not sure how often they were used in combat, or how much damage they could do compared to a traditional sword. They are undeniably horrifying – but then any sword is pretty horrifying when you stop and think about it.

The feasibility of whip swords

The first problem with most fantasy whip swords is that they are segmented. A sword has to be incredibly strong to cope with impacts, and if a blade is composed of segments, it will be riddled with joints and cracks and won’t have the required structural integrity. Sadly, most whip swords in their retracted state would be useless for anything beyond slicing brie.

The second problem with fantasy whip swords is the mechanism by which they extend. Usually, a length of cable shoots out from the grip, allowing the blade to detach into segments that can then be swung around like razorblades on a washing line. This cable can reach several metres in length, so imagine how large the coil would be if you reeled it in. There is no way that this cable would fit inside an ordinary-sized grip or pommel, and it would also have to fit in around the retraction/expulsion mechanism. This would result in a very bulky sword, which would be poorly balanced and much heavier than an ordinary sword of similar size.

The third major problem with whip swords is how difficult they would be to use. The wielder could very easily injure themselves by flailing a weapon like this – so unless there are psychic powers at play, guiding the blades, whip swords are a high risk mode of attack. Of course, it might be worth pouring time and energy into learning a weapon like this if the high risks returned high rewards, but the benefits of whip swords are questionable.

Imagine that you have a whip sword, somehow. How useful would it be in a fight? For the classic segmented versions, the user has very little control over the orientation of each blade, which makes them rather hit-and-miss when it comes to slicing and dicing. You could very easily hit a target with the flat side, rather than cutting it. So you would probably find it annoyingly difficult to cut that slice of brie.

Of course, the main advantage of a whip sword is its reach. You can slash enemies several paces away, and the speed and unpredictability of the swing might send a lot of enemies running for the hills. Still, having that extra reach might not be so useful if you only cause damage half the time – and even if the blades are oriented correctly, you can only slash, never stab. The wounds you inflict on your enemies will be very nasty, but it would always be death by a thousand cuts. In other words, this is a slow and inefficient mode of attack.

Another classic whip sword move is the entanglement of enemy weapons and subsequent disarming by yanking the weapon away. However, this is only useful if you are safely out of reach of your foe. If they are up close, then entangling their blade puts you at the disadvantage, as you have nothing to stop them lunging at you. A traditional sword can be used to parry and defend, but a tangled whip sword cannot. Even if your foe is far away, disarming them becomes a game of tug of war. If they turn out to be stronger than you, then they would be the one ripping the whip sword from your hands.

Why are they so popular then?

We have established that whip swords are heavier than normal swords, weaker when in their retracted form, and that they are practically useless in close combat. Their only benefits are as a ranged weapon, and even then, they are hard to control, and potentially very slow to take down enemies. The main reason that anyone would use one is as a show of skill, which might well frighten away your foes. They also look awesome, and can be drawn or animated in very dynamic and interesting ways – which is obviously the main reason that they keep cropping up in manga and anime. Who cares about feasibility anyway?

What strikes me as odd is that the wielders of whip swords are often the weaker, faster, more acrobatic fighters in a franchise (often women). This makes sense in the context of ranged attacks, speed and dexterity, but as we have established, whip swords are heavy and will often put their wielders in tugs of war. What must we conclude? That whip swords, as typically presented, are a bit silly.

That being said…

Some very talented people out there have built fantasy whip swords for themselves, and these are very impressive. I will admit to falling down a rabbit hole of blacksmith videos on YouTube, because it’s fascinating stuff. However, all the problems outlined here hold true for the real-life attempts, and most of them have a very limited reach.

The only feasible way for whip swords to function is if some level of magic is used to control their behaviour. Unfortunately, invoking the “because it’s maaaaagic” clause comes with its own feasibility problems within the confines of a fantasy universe. So, with this in mind, I will now do my best to justify the obsidian sword.

Why obsidian?

Obsidian is a natural glass which forms when lava cools incredibly quickly. In fact, the lava must cool so quickly that crystals don’t have time to grow. I’m not sure that I can even call obsidian a “cool rock”, because it doesn’t contain any minerals. Although it is solid (to all extents and purposes), it lacks an internal structure – which is true of ordinary glass, too. This lack of structure means that obsidian doesn’t fracture along defined planes of weakness; instead, it forms curving planes that are incredibly sharp. However, it is very brittle. No culture on Earth has ever made real-life swords from obsidian, because it just doesn’t have the structural integrity to withstand the impacts of combat.

This isn’t to say that obsidian can’t make good weapons. Obsidian was used to form small blades and arrowheads throughout the Neolithic, and is still used today, because it can be sharper than steel. The edges of obsidian blades can be three nanometres thick, and unlike metals, which all have a jagged appearance once you put them under high enough magnification, obsidian fractures in a manner that produces smooth edges, even when viewed under scanning electron microscopes. It is an incredible material, but the only large weapons ever made with obsidian are the macuahuitl – clubs with obsidian teeth, used by the Aztecs. It could never form a large blade on its own.

The main reason that I chose obsidian (besides it looking cool) is because of its strange properties as a glass. We established that one of the main problems with classic whip swords is their lack of structural integrity, and to me, an obvious solution is to have the blade reforge itself each time it retracts. Melting and re-crystallising an ordinary, crystalline solid (like metal) would still lead to weaknesses developing, but glass has no natural planes of weakness, as it is homogenous and amorphous. If the whip sword welds into glass each time the fragments coalesce, it won’t have inherent weak points.

Obviously, such rapid melting and welding would be impossible in real life – but the Highmoor universe is fantasy. It has magic. And the magic in the Highmoor universe is defined as the instantaneous transfer of energy between molecules. Our obsidian sword merely needs to borrow enough energy from its surroundings to melt the very edges of each fragment, and as soon as the fragments make contact, they are reforged by rapid chilling, which involves putting the borrowed energy back to where it came from. Energy is neither created nor destroyed during this process – but it would be a massive spoiler to explain how energy can be moved on a whim (sorry).

Because the obsidian sword is a dynamic object, constantly melting and reforming, it has incredible strength. It can still be used as an ordinary sword – and it can do more than slicing brie. By having the ability to self-heal, it can fix itself instantaneously rather than fracturing on impact. You might argue that such a sword is overpowered, but the problems that we identified earlier still remain (lack of control, death by a thousand cuts, poor defence, etc.). The obsidian sword is more of a status symbol, and a display of cultural identity – and for spoiler reasons, I’ll leave it at that.

In summary…

I hope you enjoyed this post, even if it was a little self-indulgent. I’d highly recommend looking up real-life whip swords (apologies if this puts you on a watch list), and I’d also recommend finding some images of obsidian (especially rainbow obsidian). Happy reading, and have a lovely week!