I imagine some of the warden cloak and dagger has to do with not wanting to share secrets that could give too much power to the corrupted, kings and people of power who thinks they can "make" their own little warden army to travel into the Deep Roads, awaken some old god and rule the world. I also imagine if people knew what happens to wardens who "end" the Blight, no one would want to join-- and they can't abuse conscription.
I don't know, but I do think there needs to be a tome directing the ritual and a little history to go along with it. Secrets need to be preserved, but not to the point of losing them forever.
I like the wardens and always have, but I have no illusions they are some heroic order filled with chivalric men and women. They have a single goal and nothing else matters. Everything else is collateral damage. Might be why I like them.
Again all of this is easily avoided. You can tell them why they're needed without giving them the secrets to the warden making batter. (which requires mages to make anyway and most likely requires blood magic seeing as it uses archedemon blood this is something that should remain secret because everyone will lynch them for it and see them as monsters) and what happens to wardens who don't end the blight is arguably worse.
Also no king is going to make an warden army because A. Fatality rate and B. the archedemon blood does nothing but make a warden. It doesn't impart fighting skill. They'd have to sacrifice some of their best fighters for the chance of getting wardens. And giving the batter's rather decent fatality rate I'm not seeing many kings willing to do that for their better fighters. It's just plain inefficient.
Not to mention there's not many loyal soliders that'll willing drink darkspawn blood for some insane's king dream of corrupting a old god.
And of course is the whole thing with the old gods being unreachable by anyone outside darkspawn and it's absurd. No one sane is going to attempt that. And anyone insane enough to will be killed soon enough anyway.
And on criminals it'd be wasted because those are the exact people who'd run as soon as they got the chance (and end up being forced to join the rest of the wardens by the calling so...)
I rather die in glory than die alone in the dark not to mention the slowly going insane and all those other lovely bits about the calling. These are just really bad arguments for plot dumb and the wardens refusing to give even basic information when it's beneficial for them to do so. I'm sorry but this is one argument I've been having for literally years and I've never changed my mind on it. (in fact it's only grown stronger. The wardens as an order are just no. Good intentioned but their leadership is absurd.) Kings and Queens gain nothing by knowing the wardens can kill archdemons other than the desire not to inappropriately exile wardens (and perhaps the desire to make their own but without the means this becomes a non issue). Not to mention royalty has no need for their own wardens because wardens don't have loyalty to any country in particular and outside killing darkspawn which are a non issue outside of blights have no skills in particular that they can't get elsewhere. The Grey Wardens rightfully cultivates a neutral reputation to avoid the issue of one country fearing them attacking them for another (even if it doesn't always work).
Also why do people keep saying no one will want to join the wardens if they know they'll die killing the archedemon? Um...dying saving the world? That's supposed to be the big oh no? There's only been five blights in that many centuries. That's a pretty good survival rate compared to all the other things that will killing you in the DA setting or even being a warden. Most who join the warden do it out of desperation because they're criminals or because they want to be a heroic figure. Those are the exact people who look at that and accept it. There's a reason wardens recruit the people they do.
Also we're not mentioning the slow death from the calling (with the chance that you might just turn into a ghoul and stay that way for who knows how long before finally offing it), the chance of a darkspawn spearing you in the gut, the chance of choking to death on the darkspawn batter before you even become a actual warden. I mean Blackwall's mentor died from a random darkspawn raid above surface. It's a dangerous job and a lot of them die and aren't remembered. Being the hero who killed the archedemon would be a step up for most.
Edited like forty times.