Identifying Magic Items

The DMG says: "Some magic items are indistinguishable from their non-magical counterparts, whereas other magic items are conspicuously magical. Whatever a magic item's appearance, handling the item is enough to give a character a sense that something is extraordinary about it. Discovering a magic item's properties isn't automatic, however."
The identify spell is the fastest and easiest way to find out what properties a magic item has. Alternatively, you can spend an hour studying the object and experimenting with it. You have to be in physical contact with it and it can be done as part of a short rest.
For most magic items this will be enough to uncover its full properties. However, some items might not give up their secrets that easily. In most cases you will still know how to properly use the item, but not the extent of its effects. In very rare cases some properties will not be revealed by identify but you will still be told that there are unknown properties.
For example, you use identify on a magical sword. You learn that it was made for fighting giants. You learn that attacks with it against giants and giantkin will be easier to land and will deal more damage. Additionally you learn it allows you to understand them. The only way to get the specifics is by using it in a real situation. There you learn that it is in fact a +2 weapon when used against giants and giantkin and that it allows you to understand giant but not speak it.
This rule might be a on par with the "more difficult identification" optional rule, or might be even slightly more restrictive. In some cases it is a nerf to the identify spell. However, this allows a magic item to play a bigger role than initially will be revealed. It creates a bit of breathing room for story telling purposes. These "limitations" should create a mysterious atmosphere, something that should be explored, something that will enrich the story.
Additionally there could be a way to enhance the power of the identify spell. Perhaps it could scale with the level of the spell slot that is used, meaning that a more powerful spellcaster could reveal more information about an item. These options should be explored as the need for them arises.
Note that any curse an item might have is NOT identified by study and experimentation or identify. "A curse should be a surprise to the item's user when the curse's effects are revealed." DMG (p139)
Finally, identify might reveal nothing at all. This is most likely due to it being under the effect of the Nondetection spell. This situation will however be rare. You can still learn its properties through study and experimentation, just not through divination spells, which identify is.