A Scribe class wouldn't feel right (too much like a profession,) but a scribe-ish Sage class might be workable, if I could rework it as an archetype and keep it from seeming too passive (as ckutalik points out about the scribe class in that thread.) "I solve problems by using my collected knowledge." That doesn't seem too bad. Class abilities are:
- read ANY written magic item, including scrolls;
- get an HD (or level-based) bonus when using written resources.
Unlike a Magic-User, a Sage has a built-in Read Magic. Sages can't prepare or memorize spells, but they can cast them from scrolls, perhaps with a fumble chance (add Spell Level - Sage HD to a d6 roll, a 6 or higher indicates a backfire.) They can learn spells, which allows them to create scrolls. Sage magic use is through scroll use.
The HD bonus for written resources means that Sages can decipher inscriptions, even in languages they don't know, can break or create codes and ciphers, and can get a bonus on a task if they can prepare using a reference work about a related topic. This makes Sages a little more like Magic-Users, in that what they can do isn't defined by a set power list, but by collecting "tools": in the M-U's case, spells recorded in spell-books; in the Sage's case, topics covered in a reference book.
The Sage's HD equals their maximum bonus, but their actual bonus for a given topic depends on the amount spent to acquire a reference book on that topic; use the cost for spell-books. To get a +6 bonus for animal lore, for example, an 11th-level Sage would need six animal lore reference works in a library, and would need to have the "6th level" reference work actually on hand. If they don't have this book with them, they get 1/3rd their full bonus, based on what little details they remember, or 1/2 their bonus if they have Int 18.
You could also let Sages prepare "Sage scrolls" which act like reference works for one specific task; they must be prepared in advance, with their full library handy, and must be targeted for a specific subset of a broader topic (for example: toads, for animal lore.) Sage scrolls are usable only once, just like magic scrolls, although they are not themselves magic; they're just very specific.