One of the mechanics of the setting I'm developing includes soul weapons. One of their main aspects is that they can become ethereal and pass through matter.

So, what would happen if someone poked a wall or a person while it is ethereal and turned it solid inside of them.

Assume that weapon, a sword as an example, materialize from the inside out without overlapping with other atoms or suddenly occupying the same space as them.

Assume also that for all intents and purposes, when materialized, the weapon is made of real atoms and that no matter how strong the material is, the weapon will always completely materialize.

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    $\begingroup$ Not really long enough to warrant being posted as an answer but, logically, the area in which the weapon materializes becomes an interleaved mixture of the atoms of the weapon and the wall, ruining both. There is an abrupt expansion to accommodate the atoms of the now intermixed weapon and wall pushing each other apart and some chemical reactions between the atoms of the former weapon and former wall may occur. $\endgroup$ May 17, 2021 at 22:46
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    $\begingroup$ intersecting atoms? Short answer: boom. $\endgroup$ May 18, 2021 at 0:04
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    $\begingroup$ this is really up to you since it is impossible by science we don't really have a good idea of what would occur, realistic answers could range form nothing to a nuclear explosion. $\endgroup$
    – John
    May 18, 2021 at 1:01
  • $\begingroup$ I'd say it would either force the already occupied space to be pushed away creating space for said weapon OR the atoms would overlap even after the weapon materializing and guessing the weapon can regen only the weapon would be left after that $\endgroup$ May 18, 2021 at 1:58
  • $\begingroup$ Regardless of nuclear explosion or displacement of existing atoms nonexplosively, if you poked a person with it, it would very clearly be lethal. $\endgroup$
    – jdunlop
    May 18, 2021 at 2:01

1 Answer 1


Not much

You state that the weapon doesn't overlay the object. Therefore it will have to push the material aside.

The effect is similar to just poking it in "really fast". A rock will crack, perhaps, but even titanium will just end up with a weapon-shaped void when you remove it.

The fun part is looking at ways to abuse this. Armour-piercing? Leatherworking? Mining? All of these need you to part something tough.

If you have a sufficiently-strong exterior, you could use this to compress neighbouring matter into fusion-grade density, but that's unlikely to ossur when a human can get close enough to use the ethereal version.

Edit: A comment points out that this makes armour ineffective unless it's "warded": move your sword to be through some part of your opponent, and let it materialise. Suddenly all plate is useless. You also don't have to waste time pulling it out, you can just turn it ethereal again (probably, depending on those rules).

If the reforming is near-instant (say, vanish-reform 2000 times/second), you can make a "screeching blade" which can cut through anything. The screech would be caused by air being displaced.

  • $\begingroup$ Mining? Drilling bore holes for dynamite just got a lot easier 😁. (Mining, quarrying, tunneling, certain forms of excavating... There's probably applications in manufacturing, too, and that may be just the start. Say, there's a trope about how the most useful use of superpowers is otherwise-mundane applications, though I forget which one offhand.) $\endgroup$
    – Matthew
    May 18, 2021 at 3:53
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    $\begingroup$ Hey, you're right. The biggest advantage of a weapon that works as OP describes is that it will always go in, no matter how much force it would normally take to do that. If it acts like something that starts out as a thin line and expands to its full size, no intersecting atoms, then I'm pretty sure the result of materialising it in something will be much the same as driving a normal sword into that thing - but, though it's easy enough to drive a sword into a human, it's not normally so easy to do to steel armour. And, as you say, mining. $\endgroup$
    – A. B.
    May 18, 2021 at 5:30
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    $\begingroup$ It doesn't "have to" push the material aside; the material may push it aside instead. For a stone wall or something, the immense pressure of the surrounding atoms of the wall against the materializing atoms of the sword may either crumple the blade of the sword (it's very thin as it's initially forming) or cause the sword to be pushed outwards from the wall with considerable energy. $\endgroup$ May 18, 2021 at 14:13
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    $\begingroup$ Thanks! The screeching sword is a great idea! Gonna use it for sure! $\endgroup$ May 18, 2021 at 21:37
  • $\begingroup$ @GrumpyYoungMan True, I hadn't thought of that, although whether that would happen might depend on the shape of the weapon. $\endgroup$
    – A. B.
    May 19, 2021 at 7:57

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