Far too big
Seeing as Apocrypha is and will continue to be a large part, if not the majority of the Encyclopedia, putting this in a message box strikes me as over-kill. Simply changing this template into an invisible "Category:Apocrypha" tag would fully serve its purpose.
If a reader cares enough about the canon sources to want to know where the article is derived from, they can simply look at and browse those categories. For someone who genuinely doesn't care whether it's canon, as long as it paints a coherent and detailed picture of Ermarian, there is no need to clobber it in with a warning label above the article. (And now you know my opinion on "apocrypha"...)
The nice thing about making it a template is that we CAN change these things.
EE does two useful things. One of them (which really should be taken better advantage of) is provide a place to collect and organize general info from scenarios and other additions made by people besides Jeff. The other is to present a coherent and authoritative picture of game canon. I know the the first one was originally the main goal, but the fact is that the majority of EE *is* perfect game canon at this point, and it seems silly to me not to provide sufficient citations and labels to preserve this function, when it is so easy to do so.
The other problem is that which articles do and do not "paint a coherent and detailed picture of Ermarian" is somewhat subjective. I will always despise the Relhan king-list. I know there are bits here that Drakey doesn't like, and I'm sure that goes for others as well.
What if the template became a small box that said simply "Source: Whatever"? That would preserve the information without being quite so alarmist. "Source" could link to Canon (or we could move it to Sources). Say...
Note that this box code does not include the actual categorization, to avoid categorizing this talk page. I also think it might look good in a pastel background, which seems to require editing a "class". Actually, it needs a lot of help in a lot of ways. Aran? --- Slarty 16:29, 1 March 2007 (PST)