You are wrong about Shiro and right about Michael. In all likelihood, though, Michael's description is probably just not counting the bonus that Michael will likely receive from True Aim. It ignores it on attack, too, after all. And it doesn't mention the likely bonus to his Athletics defence from Righteousness.
That aside, the way the Power is written is fairly clear. The writeup should take precedence over the examples if there is a contradiction.
It's debatable anyway. It says when it's "swung" with true purpose, which sounds like it's talking to an attack to me. You don't really "swing" the sword when you're defending.
Dude, the way the Power is written is clear. Very clear. The sword cannot be used except in keeping with its purpose, and when used in keeping with its purpose it gives +1 Weapons.
If you want to adjust Michael's power to fit (your interpretation of) his narrative role, use his Aspects. That's what they're for.
The "restriction" does not actually restrict anything.
Let me put it this way...say the Sword is like a company car. You can use it for whatever you like, so long as it's accepted uses of a car--going places, getting groceries, etc.--and not against company policy or illegal in some manner. But you're only going to get your gas reimbursed when you use the car for explicitly company-backed uses (going to conferences, seeing clients, getting to and from work).
The sword's like that. Michael can use it for things that don't go against God's agenda--killing demons and vampires and such--but he doesn't get the full benefit of the sword's power unless he's particularly on a mission from God.
But in any case, there are situations where Michael would want to use the sword, but can't use that stunt because of the restrictions--while a weapons specialization has no such restriction. Ergo, the canon
power has a stricter restriction than this homebrew
stunt, which is backward.
You don't need high Resources or Craftsmanship to own armour. Characters are assumed to have the tools for their job. And even if you start without armour for whatever reason, once you get some you can keep it until something happens to it.
To own armor? No. To own the toughest, sleekest, best available armor? Yes. Having the tools for their job doesn't mean they automatically have Armor:3 that fits under their shirt and is light, breathable, and doesn't restrict their movement.
But I know that I, personally, would have a much easier time wearing chainmail than carrying a battle axe. One would be uncomfortable and likely to get me weird looks, the other would get me arrested.
Again: Only if you're being foolish and carrying it around as a naked blade. And...really? Have you
tried wearing chainmail? Even football pads, made of comparatively lightweight plastic, are not something you want to wear all day.
And, frankly? You can't. If you have any sort of regular job, it's going to have a dress code that does not include chainmail. Inherent in the Dresden world is a need for supernaturally inclined characters--be they supernaturally powered or mundane but knowledgeable--to be discrete and avoid attracting undue attention because of the complications that ensue.
Carrying around a sword out of sight in a dufflebag isn't going to get you stopped unless you give people reason to check your bag. Walking around in full body armor all the time is going to get you all kinds of attention from everybody, including police officers who wonder why someone is walking around in full tactical gear. It really isn't something you can get away with.
Relatively new 'covert' vests can be rated both IIIa (good vs pistols and shotguns) and stab/edged II (which I think is rated for everything other than things like full body charges with a spiked weapon.
In the game, this is somewhere between armor 1 and armor 2, depending on how you want to model things.
A vest with class III or class IV plates (which will protect against rifle fire) can't really be worn covertly. That is, you can't say, shake hands with someone and have trouble noticing they are wearing armor. That's somewhere between armor 2 and armor 3 in game terms.
If differentiating between various armors became important in the game:
Armor 1:
a variety of 'home made' protective gear, just as motorcycle leathers, jumberjack and/or various tool resistant clothing (lumberjack chaps, etc). Not usually concealable.
Or old/reconditioned modern armor. concealable.
Resources 1 (around 200-300 USD to acquire)
Armor 2:
Actual 'plate' or 'mail' style metal armor. or 'modern' concealable armors
Resources 2 (around 400-800 USD for modern armor, considerably more for metal armor)
Armor 3:
Technologically reenforced plate or mail armor.
Non-concealable modern armors (includes helmet, fragment goggles, etc.
edging into resources 3 (An armor 2 vest, and then another 400-800 USD or so for the strike plates, add several hundred more for things like helmet, goggles, knee and elbow pads, etc.
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This would mean that most police you'd meet in the US would have armor 2, and most US troops you'd see in Iraq or Afghanistan would have armor 3.
I think you're really lowballing the cost of armor, there. I'd have to check the chart, but offhand I'd either double the Resources ranking needed for each set of armor, or attach aspects to cheap versions of Armor:2 and 3.
Also, there's a difference between keeping something from killing you (which most body armor aims to do) and being able to negate the force. Something that protects against handgun bullets is just keeping it from penetrating, but it can and will hurt like hell and potentially injure you. So I'd say that the standard police vest is probably Armor:1, military/swat body armor is Armor:2, and maybe bomb disposal suits are Armor:3.