Except of course not telling players things like this their characters are unaware of.
Literally impossible.
Characters don't know about Aspects, dice rolls, skill ratings, Powers, or Fate Points.
You have to inform your players about stuff their characters don't know.
Of course, there are plenty of places you can draw the line and from what I know about your approach it sounds reasonable. But I'm dead certain that even you inform your players about things the PCs don't know.
No, I'd apply that standard (ie: non-spellcasters need an Assessment to tell how badass a spell is) pretty much universally. It'd usually be a Lore assessment, though I might allow Scholarship or (in cases like the stone wall) Craftsmanship if those seemed appropriate.
Could work, but I dislike the idea of giving spellcasters special extra abilities beyond what's in the rules. They really don't need that.
I usually don't tell characters mechanics stuff, just what appears to have happened, ie: 'You punch him and he loses teeth', or 'He raises a wall of fire'. I tell them any Consequences they inflict, but beyond that I usually don't worry about giving them mechanical details too much, as, IME, it tends to make things less narrative and more mechanic focused, which I personally like to avoid...if doing things this way the only one who needs to avoid metagaming is the GM...and he needs to do that anyway.
I never tell the characters anything. (Were you making a distinction between character and player there? I can't tell.)
But I can't really be bothered to keep basic mechanical stuff secret from the players. It's a hassle, especially when Aspects get involved, because when somebody misses they'll often want to know whether they could hit by spending a Fate Point.
Would someone like to clue me in as to just what it is about a solid wall of stone (or other opaque solid substance) seen only face-on that tells you, for instance, how thick that wall is?
A 2-shift stone wall is probably like a low fence made of rock. A 12-shift stone wall is a huge-ass granite dome or something similar.
That's the way I run it, at least. Looking at the thing lets you tell whether you have a decent shot at getting through.
I'm actually kind of surprised that so many people would make a 2 shift and a 12 shift block look identical.
It's unbalanced if the invisible dome is invisible and he stone wall looks like a stone wall?
If the stone wall gives away useful information to your enemies and the invisible dome does not, the dome is better. They cost the same. That's not balanced.
Wizards have to do a Lore check before they can counterspell anything--including blocks. So wizards, who know magic inside and out, do not automatically know the strength of a spell they're up against. Why would an untrained vampire know exactly how strong a wizard's block is relative to his own strength?
I've said repeatedly that an untrained vampire wouldn't know exactly how strong a wizard's block is. But they'd generally be able to tell if the block is so strong as to make attacking futile.
I'm a pretty mediocre fighter. Fair Fists, tops. But I can tell whether my punches are likely to land long before I throw them.
This isn't hard. Anyone with even the slightest skill can tell when they're up against a (mundane) defence that outclasses them completely.
Magic could be different, but I don't see any particular reason to make it so.
That's rather the point--there is no way for them to know. Your players don't find out an enemy's defense roll until they attack and the enemy defends, right?
They know when the roll is made. That goes for blocks and defence rolls and pretty much everything else.
I see it the opposite. That knowing the total block strength is something the players may know, and the characters don't. So letting all the characters automatically know the power of each spell is metagaming. It's a character benefiting from the knowledge the player has that the character has no way of knowing.
Ugh. This is some pretty ugly circular reasoning, dude.
If you start with the assumption that people can't tell how strong a block is by looking at it casually, then obviously you'll reach the conclusion that it's not appropriate for people to be able to tell how strong a block is by looking at it casually.
But if you assume that blocks look about as strong as they are, then the question of metagaming does not even arise. Characters know more or less what players know, completely legitimately, so OoC knowledge cannot be exploited.
Sophisticated? No. I'm just saying that the game, being a roleplaying game, is meant to have the characters stay in character and their actions make sense. Having your vampires not know things that a vampire wouldn't logically know isn't "stupid," it's in character.
The issue is the nonsensical elitism, not what it's appropriate for characters to do. Don't tell people they're playing the game wrong. Just don't. Ever.
Informing people how the mechanics work is okay, but even then you have to be careful to avoid passing moral judgement. This can be tricky and I'm sure I've screwed it up a few times, but I try. And so should you.
Also, an action being in character does not make it not stupid. IC stupidity is totally a thing. And that's okay, but it's not mandatory. Especially if Compels aren't involved.
Because hey, in real life, and in the books, characters do not always make the most intelligent decisions. So yes, characters not always making the most optimal choice in the heat of battle is more "accurate" than everyone knowing things they shouldn't have any way to tell and acting with the utmost efficiency with every actions.
I mean, look at the books. Enemies are shooting, clawing, and blasting at Harry's shield spells constantly. By your argument, none of them should ever take a shot at him because they know his shield is stronger than their ability to attack. But that doesn't happen. Enemies only get a sense for the other side's abilities when they test them.
First, Harry's shields suck and attacking him when they're up is pretty sensible. Harry is like the perfect example of what not to do with evocation blocks.
Second, Compels are important. They're what prevents ultra-rational decision making.
And third, characters frequently scope one another out at a glance. It's not even slightly rare.
Suppose the Merlin were to throw out a weapon 12 zone attack. Everyone can tell that that's a big attack. I don't see much reason to treat blocks differently.
PS: Is this argument connected to the original one? I don't see much of a link. But I'm OK with topic drift, as long as the rest of you are.