how well would a magical scale armor-strength cloak work as armor?

Question

the cloak covers most of the body, usually down to a foot above the ground. it's stiff enough and built to sort of spread out as it gets lower at a constant rate, and underneath the cloak is the person. they do have holes that they can poke their arms out of, so being able to use your arms isn't an issue. (i know you can't see them, but they're there trust me.)

the only negative could be that it's hard to hold weapons, but that's fine because you don't have to. in this world you use crystals. crystals summon either light or dark magic out of them depending on the type. but usually it's light magic. they are both essentially the same thing so it shouldn't matter. so they can summon light magic out of a crystal, which is usually an object or liquid that's white in color. they can then used this as a floating knife or a sword or a shield, or even just a third hand if they're good enough. the more complicated the harder.

this is relevant because each cloak has a big light crystal on them that they can use for many purposes. most people can afford these cloaks, and it's pretty standard to the point that if you didn't have a cloak, it'd be like not wearing shoes in our world. like being homeless. having these cloaks is like having free body armor. using crystals to protect yourself is pretty standard for humans. this is a god-made world after all, so of course they'd make it "evolutionarily" instinctual. so when they see something coming they'll use the crystal on their cloak cover them in light magic. or if they're better at it, then they'll make a full on shield in the specific direction to provide specific protection.

all of this being said, i want to know about the covering. how good would that be if a thin one-inch sheet of light covering the entire cloak was about the strength of scale armor that the romans used?

specifically asking for thing like, explosive shots of light or dark magic, giant swords, spears or arrows, all made out of magic. this is the standard civillian, not the protagonist/royal/knight armor. just letting you know. i just need to know how the average human survives things.

if i'm missing any sort of data, i'll gladly figure it out and add it. i haven't been here for a while, so be soft on me if i'm doing anything major incorrectly.

visual: ignore the baldness and blandness, i'm still working on it, this is just to give you a visual.

Answer 1

Cloaks make lousy armor

One reason the traditional armors work as armor is because they're basic characteristic makes them either difficult to penetrate or capable of diffusing the force before it connects with the body.

But the important reason is that armor is, to one degree or another, stiff.

Imagine a piece of cloth that moved like cotton and could be worn as a shirt — but had the penetrative capabilities of the finest kevlar bullet-proof vest. The bullet absolutely positively couldn't get through the shirt.

You're still dead because the bullet happily pushed the shirt half-way through you. Yup, the shirt never tore, and the medic simply needs to grab two sides and jerk to pop out the bullet, but you're still dead due to the half-inch wide, three-inch deep hole in your body.

Unless you let magic happen

Magic is wonderful. It solves all problems. You could declare that the characteristic of the magic cloak is that the faster the object hits it the stiffer it gets such that you couldn't even be casually poked. Bullets? Hah! They bounce right off you! Of course that does have a drawback (not that your world has machine guns, but work with me for a moment): all someone needs to do to completely immobilize you is unload their vulcan cannon at you. The cloak completely stiffens and you sit there with your head sticking out like the proverbial dead duck. Your enemy laughs and taunts, leaving the last bullet for your head.

In a sense, you've asked this question too early

We don't know a lot about your magic system. There's no way to know if your magic system would allow what I just described to happen. Of course, it's magic, if you want that to happen you can! But when it comes to balancing magic systems the devil really is in the details.

The question isn't, "can I do this?" Of course you can! It's your world and your magic system. Do what you want. The real question is, "Is this ability well balanced in my magic system?"

Unfortunately, you've not described your magic system enough (no where near enough) to answer that question. For example, what's a giant sword? What does it take to wield one? What consequence should exist to the sword bearer? What consequence should exist to the cloak wearer? You don't want either to be too powerful — but neither do you want either to be too weak. Can the cloak block everything? Then it had better be rare — but you explained that it's almost as common as milk. That would suggest it should block a knife attack, but never a giant sword.

I'm looking forward to your next question, but before you ask it, remember that worldbuilding is about rules and systems — not plot, descriptions, or choices. What you've basically done here is described an object and asked "does this work?" Except it was like describing a car's color and the curve of the fender and the design of the grill and then asked, "does this car work?" We don't know, because you didn't describe the road or the engine or the brakes or the tires or the cost of gas or the driver's skill... That's what we need to help you build a magic system.

So, think it through. Make sure you're asking about the "workings of" and not the "design of" and then hit us with the next question. We'll have fun helping you iron our your world.

Answer 2

Let me shortly repeat and interpret how you described the 'shield effect' of your cloak:

(…) if a thin one-inch sheet of light covering the entire cloak was about the strength of scale armor that the romans used?

So as I get your thought there is a thin cover of magic upon the outmost layer of your cloak which follows every movement of the cloak but (as it has the strength of steelmade scales) the cloak does not follow the movements of the layer. Things hiting the magic layer either are repelled or penetrate it, depending on their strength compared to the magic power. So the answer is at easy as this: Your magic armour and the magic weapons interact identically to a real armour and a real weapon of the same specifications. As this is different for every case (sword, arrow, explosion and so on) you have to analyse this newly with the specific Details every time.