Working off of a previous question about armor, imagine yet again a world where there exists a metal

comparable to high grade steel, however instead of steel's density of ~8 g/cm³, this material has a density less than even aluminum at ~2 g/cm³. The ease/difficulty to work it is roughly comparable to steel. By terms of rarity it is comfortably more costly to acquire than steel is to create, but not nearly enough so to make it considered a precious metal.

The previous question dealt with armor; I want to consider weapons.

Setting is an alternate 15th century. This imaginary metal has been in use for around two centuries, enough time for plenty of weapons to be forged, and for tactics to evolve to take advantage of its unique property (for the purposes of this question, you do not have to consider the effects of using this metal in armor). How would this lighter metal change what weapons are used on the battlefield?

The way I see it, in war there are cases where light weapons are better, and cases where heavy weapons are better. I just can't figure out how that balance would play out on a large scale.

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    $\begingroup$ It would be good if you include the question at the very top of the post. You have it (only) in the center, which is hard to spot. First impression is “what’s the question?” $\endgroup$
    – JDługosz
    Commented May 25, 2017 at 19:05
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    $\begingroup$ @JDługosz Eh? I could only see the difficulty in understanding the question if you skipped the step of reading it. $\endgroup$
    – Ranger
    Commented May 25, 2017 at 19:07
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    $\begingroup$ Yes; people will skim to decide if it’s interesting. This is a “burried lede”. It is common here on WB to use bold to make it stand out, in this case. But it’s better to include an indication of the question at the top. $\endgroup$
    – JDługosz
    Commented May 25, 2017 at 19:09

3 Answers 3


I intend for this to complement, not replace, what Sam said.

There are many, many types of weapons used by a variety of soldiers in the medieval era (although the 15th century is more of the Renaissance-era), designed for various purposes. I will attempt to cover the major ones.

Blunt-force weapons

As Sam said, these weapons include maces, mauls, war-hammers, and other weapons designed to deal impact damage to bones and tissue without penetrating armor. You won't likely see any use of your ultra-light high-strength metal (which is less dense even than titanium). These weapons rely on momentum for their damage potential and require significant mass.

You might possibly see your lighter metal in maul chains to allow for more of the overall mass of the weapon to be concentrated in the end.

Edged weapons

There are some advantages to lighter edged weapons, again as Sam said. Faster movements allow for better targeting of the moving openings in armor and improved slashing attacks. Off-hand weapons like parrying daggers (though not really used on the battlefield) would also benefit from being lighter, allowing better protection and faster parrying.

Thrusting weapons

Personally, I think thrusting weapons (mostly thrusting swords) have the biggest advantage in being lighter without sacrificing strength, as it allows you to impart more force in the thrust, improving penetration of mail and the underlying tissue.

Ranged weapons

You won't likely see much use in ranged weapons, except perhaps in the previously steel parts of crossbows. Those, however, are peasant weapons and it's unlikely a noble would spend extra money to outfit his peasants with lighter crossbows. Crossbow bolts and arrows rely on momentum for their penetration - too light of an arrow won't penetrate the target, so those are off the table.

Early firearms might benefit from a light, strong material like yours, but those early projectiles likewise depended on their mass to do damage.


Polearms, again, are peasant weapons. Though they would benefit somewhat from lighter heads, that's not going to offset the generally very heavy wooden pole.

Material rarity

Given the overall rarity of your wonder-steel, the weapons made will likely be restricted to nobles and perhaps their personal guard. The bulk of armies, which were generally peasants, were outfitted with cheap arms and drew strength from numbers and strategies (and having more people than the other guy).

TL;DR - Overall, I believe your material is more likely to impact duels among nobility than it is large-scale warfare.

  • $\begingroup$ Why lighter thrusting weapon should have better penetration than regular kind, and lighter arrow worse? $\endgroup$
    – Mołot
    Commented May 25, 2017 at 22:05
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    $\begingroup$ @Mołot The momentum of an arrow is based on the arrow's weight, the momentum of a melee weapon is based on the weight of the wielder. $\endgroup$ Commented May 26, 2017 at 13:50
  • $\begingroup$ This is a far better job than what I wrote, it's incredibly detailed and goes into specific cases, while touching on weapons I missed +1 $\endgroup$
    – Sam Worrod
    Commented May 26, 2017 at 20:13

Similar to comments in your earlier questions, there were 2 main types of ways to injure knights in medieval times.

Blunt Force

Weapons such as maces and war-hammers fall into this category. The source of the damage comes from the force of the weapon hitting the person, as opposed to cutting the person. This relies more on strength. In this case, the normal metal used in the past is preferable here, as it better suits their purpose.

Bladed Weapons

The other way to injure knights was to target the areas where the joints were exposed, and attack there. This relies more on technique and speed. For these weapons, the stronger, lighter metal is preferable as you can make stronger blades that don't weigh as much, allowing for quicker movements.

In terms of how this would work on the battlefield and the distribution of weaponry, the issue with plate mail in the past was how much it took to make a set, which is why only knights would have it. This new metal is less common than steel, which means even less troops will be able to use it. Outfitting an entire army is a bit excessive, so I don't see that making a huge thing.


A light weight metal with equal properties to steel would make for longer, more deadly swords and daggers. The important properties that need to be the same for weaponry are strength, hardness, and strength/volume. Longer swords allow the user to hit an opponent further away without risking being hit. If you simply stretched out a sword to make it longer it would lose stiffness and strength, so more volume of metal (aka mass) needs to be added to preserve its performance. The problem is adding mass to a sword makes it slower to swing and thrust, and more tiring over time to handle. Your 4x lighter metal would make a huge difference here - imagine a 2-handed sword that could be wielded like a saber. Or watch a video of a saber duel, but imagine the swords are twice as long and do 4x the damage on contact.

Daggers of the same size as steel daggers would be lighter while providing the same strength, making them easier to conceal and faster to wield.

If cost were no object a lightweight metal could replace the wood in polearms, similar to how titanium, aluminum and carbon fiber composites are used in modern airplanes and spacecraft.

Titanium hammers for normal people exist in our world and can be bought at home improvement stores. They cost about 5x an iron hammer but perform about 50% better than an equivalently sized steel hammer. Their lighter weight, equivalent strength, and titanium's unique elastic properties contribute to their higher performance, at least for the purpose of driving nails. Many professional carpenters swear by them.


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