How can I tell the difference between old and new Legendaries?

In patch 1.0.4, lots of Legendary/Set items received an upgrade. However, this upgrade was not applied to existing items. In the Auction House, these items are differentiated between when searching by adding [LEGACY] to the end of the legendary name and new Set items have new names altogether. However, the actual item descriptions don't appear to have anything to distinguish them.

Is there any way to tell the difference between a 1.0.3 Legendary and a 1.0.4+ Legendary? This is most crucial when trading unidentified items.

Solution 1:

There's no definitive way to distinguish between unidentified legendaries pre or post 1.04. If it is level 63, it is likely to be a new one, but not in all cases.

In many cases, there is no easy way to tell whether even an identified legendary is old or new. Some new legendaries (and all new sets) have new names, so in those cases, there will be no confusion.

For the remainder of the items, it may be discernable if you compare the affixes with an old iteration of the item. If the legendary has a 'special power', it's new. If it has great damage, it's very likely new. In all other cases, it is either old, or it is a new one with a mediocre stat roll.

Solution 2:

The item level of the object might point that it is the 1.0.4 legendary :

Legendary items used to cap out at ilvl 62, making it near impossible to find a weapon that had strong DPS. No more. We’ve promoted a LOT of the new Legendaries so that they will roll at ilvl 63

Source is here

So if you see a legendary with ilvl 63 it is one of those new legendaries.