There's something I don't fully understand about cursed items

[Dr TPK]

You're the DM. The PCs find a Sword -2. Detect magic says it radiates strong evocation. Then they identify it. The percentage roll fails. What will the Identify say about the sword?

Of course you can say "nothing". That's ok, but Identify usually gives all the information except that the cursed aspect is rarely revealed.

The same goes with some other items too. Is it just that Identify says "nothing"?

[Seto]

You're the DM. The PCs find a Sword -2. Detect magic says it radiates strong evocation. Then they identify it. The percentage roll fails. What will the Identify say about the sword?

Of course you can say "nothing". That's ok, but Identify usually gives all the information except that the cursed aspect is rarely revealed.

The same goes with some other items too. Is it just that Identify says "nothing"?

In general, Identify tells you what the object would be if it weren't cursed. In that case, a +2 Sword. Or for an Amulet of Localisation, "An Amulet of Antidetection".

[Dr TPK]

In general, Identify tells you what the object would be if it weren't cursed. In that case, a +2 Sword. Or for an Amulet of Localisation, "An Amulet of Antidetection".

Thank you, Seto, but could you justify why do you say that it would register as a +2 Sword, please?

[Seto]

The DMG, in the relevant section ("specific cursed items", it's the only one that discusses Detect Magic), says that "A simple Detect Magic spell reveals an aura of inaccurate school and strength, that you would find in a similar non-cursed item". (I'm translating from my French version, so the wording is probably not exactly the same in the English version).

I think the "similar non-cursed item part" takes precedence over the "inaccurate aura" bit. That's to say, it detects as the wrong aura/strength when the cursed item's aura would be different from a normal item's aura. For example, an Amulet of Location would effectively be a Divination effect, but detect as Abjuration, because the Amulet of Nondetection is Abjuration.
What is the contrary of a -2 Sword ? A +2 Sword. So in that case it would detect as Evocation, as you said.

As for Identify ? I don't see it written, but if the PC is fooled, it makes sense that it would yield the same result as Detect Magic, that's to say the opposite of what the item actually does, or a non-cursed item.