drjones said:
I think unless the world is low magic it might be reasonable to assume that those in the adventurer/treasure gathering trade might be more knowledgable about magic and items even if they are not professional wizards, especially after the first few levels.
You might have that backward.
In a very low magic world, say, one where only a dozen magic items have ever existed, people will have heard of most of them. If they should stumble upon them in their travels, they would instantly recognize them. Just like you might recognize the Eiffel Tower if you happened to travel to Paris and see it.
In a world that is still low-magic, but one where every famous super hero probably has one or two items, many of those would still be legendary and easy to recognize by anyone steeped in the lore (though some items might be fairly obsure).
In a world where magic is much more common, where every two-bit hero has a dozen magic items and every superhero has a treasury full of magic itesm, there are potentially millions of magic items in the world. Nobody can know of all of them. There could be literally a million +1 swords, and most of them look very much like each other, or like other ordinary swords, or maybe even look like +2 swords. No way anyone would be able to tell those swords apart easily.
Of course, in that world, people would strive to find ways to identify the magical properties of items. Every street merchant would have a magical spyglass he could use to scan an item and determine its properties, and adventurers would be hauling such items into dungeons with them to identify stuff on the spot.
D&D generally falls somewhere between those low-magic settings and that common-magic example. Still too many items for even the most astute sage to recognize all of them, but certainly the flashy items, or legendary items, or even trademark items (the Red Cloaks of the Scarlet Brotherhood), might be easily recognized by the well-educated.
For the rest of the stuff, clever adventurers have general knowledge about many types of enchantments on items, and have simple means to divine typical powers, such as the jumping/running/climbing/water walking tricks to figure out a pair of boots.