I have a sword. It is an excellent sword, but it has one strange proprety. Any cuts made by the sword, regardless of their size or depth, do not bleed.

Unfortunatly, my sword was passed down to me from my Father, and to him from my granfather, and so forth. I don't know how it works. Could you explain to me?

What I'm basically asking: can you have a sword that, regardless of the wounds made, does not cause bleeding? If so, how?

Notes and considerations:

  • The sword is made of any modern material, like steel, fancy alloys, etc.
  • The sword can be any sword-like shape, chosen by you, within reason and within the bounds of the material.
  • The sword can have attachments like, say, a heating element as long as you can figure out how to use it. All tech must be doable now.
  • Ask for more info in comments if you need it.
  • 2
    $\begingroup$ Looks like you're looking to handwave something impossible. So pick your favorite form of technobabble, handwavium or the ever popular magic and make something up. It will all be equally plausible. Since this is a question with many valid answers it is not a good fit for this site. $\endgroup$
    – sphennings
    Jan 19, 2022 at 16:08
  • 1
    $\begingroup$ @Firedestroyer As a general rule idea generation, discussion prompts, or any question with many valid answers is not a good fit for this site. You can always edit your post to ask something more specific. Do you have an idea in mind you'd like a reality check on? $\endgroup$
    – sphennings
    Jan 19, 2022 at 16:12
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    $\begingroup$ This is a question about technology, moreover, it asks for solutions based on currently known science and existing technology. Yes, it may very possibly be that there are multiple solutions to achieve the desired effect. But it is the case for every single question dealing with technology on this site. If this question is closed as 'opinion-based' then 99% of questions on this stack should be closed as well. $\endgroup$
    – Otkin
    Jan 19, 2022 at 19:09
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    $\begingroup$ @Otkin if I did have a nice or interesting negative answer, I'd have given it. Its a bit of a slog noting down all the reasons why stuff like this doesn't work, and it isn't particularly satisfying to do. $\endgroup$ Jan 19, 2022 at 19:34
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    $\begingroup$ This isn't plausible given current technology. I'm assuming the mention of technology means you don't want magical explanations. With something like Star Trek level tech, it's depositing micro-force-fields inside the wound, one per capillary. It's unclear how long they last, or if they disappear when no longer proximate to the sword. Perhaps also clotting agents, so that when their juice runs out, the wound still doesn't bleed. I don't consider this question well-thought-out, or a good fit for the site. VTC. $\endgroup$
    – John O
    Jan 19, 2022 at 20:56

3 Answers 3


It's a self cauterizing blade

Cauterization (or cauterisation, or cautery) is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or minimize other potential medical harm, such as infections when antibiotics are unavailable.

The practice was once widespread for treatment of wounds. Its utility before the advent of antibiotics was said to be effective at more than one level:

  • To prevent exsanguination
  • To close amputations

What the sword does is, in simple terms, burning the freshly cut tissues to prevent blood loss. It can either do it by thermal effects or by chemical action

Tools used in the ancient cauterization process ranged from heated lances to cauterizing knives. The piece of metal was heated over fire and applied to the wound. This caused tissues and blood to heat rapidly to extreme temperatures, causing coagulation of the blood and thus controlling the bleeding, at the cost of extensive tissue damage. In rarer cases, cauterization was instead accomplished via the application of cauterizing chemicals like lye.

Electrocauterization is the process of destroying tissue (or cutting through soft tissue) using heat conduction from a metal probe heated by electric current. The procedure stops bleeding from small vessels (larger vessels being ligated). Electrocautery applies high frequency alternating current by a unipolar or bipolar method. It can be a continuous waveform to cut tissue, or intermittent to coagulate tissue.

Many chemical reactions can destroy tissue, and some are used routinely in medicine, most commonly to remove small skin lesions such as warts or necrotized tissue, or for hemostasis.

  • 5
    $\begingroup$ For your next trick, suggest what the author's grandfather used as a power source for such a thing ;-) $\endgroup$ Jan 19, 2022 at 16:17
  • 2
    $\begingroup$ @Starfish prime Nuclear diamond batteries. $\endgroup$ Jan 19, 2022 at 16:24
  • $\begingroup$ @Madman the power density is too low. Human beings are hella soggy. $\endgroup$ Jan 19, 2022 at 17:06
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    $\begingroup$ A sword able to flash cauterize a wound to the abdomen, or a cut through the femoral artery, would be hotter than the sun. I for one would not want to have that sword only a few inches away from my body. $\endgroup$
    – AlexP
    Jan 19, 2022 at 19:20
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    $\begingroup$ As for non-thermal methods: Electro cauterization or laser cauterization would be less flashy, but you could not fit an adequate power supply in a sword to do it fast enough to seal a wound as it passes through using modern technology. Chemical cauterization is your best bet because it can leave behind a material in the wound that would have a lot more time to work. However, common chemical cauterizing agents like silver nitrate or hydrogen peroxide do not last long in open air, and this sword is already several generations old without ever having been refilled $\endgroup$
    – Nosajimiki
    Jan 19, 2022 at 22:28

Q: The sword is made of any modern material, like steel, fancy alloys

Ok let's suppose modern times, hand-waive the reason why the sword is used..

When the owner would have inspected his sword, there would be no need for a letter

The strangeness of the sword can be explained: the owner keeps the sword in a holder, never touching the tip of that sword, apparently.. He inherited the sword and just uses it 2x per month for executions ? And he wonders why he doesn't see any blood ?

The sword tip is cold. Or it seems cold.. the equivalent of 55 Kelvin or so.

Why is that sword tip so cold ?

His father was a time traveler who got lost in our modern times. The sword was a souvenir, but it is out of phase, because the time deviation controller's batteries ran out. It is shifted back in time, currently a few seconds. Everything it touches seems to come to a standstill, more commonly referred to as "frozen". To be precise: it invokes a sudden minus impuls for every particle, in the direction they came from. The time deviation cancels out fluids instantly, because it stops the molecules.

Fatal heart attack

Your stabbed victim dies rather quickly, because blood circulation gets messed up: the sword top will freeze any body fluids it comes into touch with. It will not cut, but effectively block the veins. When e.g. your major artery is hit, you'd get paralyzed and quickly die of heart attack, without any blood loss.

  • 1
    $\begingroup$ From the OP, "All tech must be doable now." If causality-violating time travel is ever devised, your answer will have always been fine, but it hasn't yet ever been devised and so hoping that you might will have been correct is probably not going to have been enough to meet this requirement. $\endgroup$ Jan 19, 2022 at 20:35
  • $\begingroup$ Hmm ok @StarfishPrime so I should produce another explanation for the sword tip getting extremely cold ? Suppose this time traveler has arrived in our time and left his sword to his son ? Something completely different.. AND science based.. $\endgroup$
    – Goodies
    Jan 19, 2022 at 20:41
  • $\begingroup$ Edit.. @StarfishPrime I shortened the introduction, changing the suggestion of unfeasible high tech, and let the father be a lost time traveller from the future. $\endgroup$
    – Goodies
    Jan 19, 2022 at 22:15

2-part epoxy

Many modern military med kits include a tube of emergency superglue. When you don't have time to properly dress a wound a bit of glue can seal it up nice and fast. The problem is that these glues are either air or water activated; so, if you put some on your sword, it will be spent in seconds, and certainly have not effect after generations of this sword has existing. Instead you need a 2-part epoxy.

A 2 part adhesive stays in an uncured state when separate, but can very quickly harden when mixed. So your bloodless sword contains the adhesive part of the epoxy on one side of the sword and the activator other half on the reverse. You could design the scabbard to only allow the sword to be inserting in one orientation (it needs to be a curved sword) to make sure that you don't reverse the sword and glue it into its scabbard. These materials can be set into the fuller of the blade and made to resemble a decorative lacquerer inlay; so, when the blade cuts a small amount of each component is wiped away and mixes when the sides of the cut comes together (which wounds tend to do before rebounding back open). It rapidly hardens into a plastic like substance sealing the wound and stopping the bleeding.

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