Is there a way to discern if the magic of an item is a “trap” or a “property” of the item?

To put things into context:

We just entered the final room of a dungeon and we found some magic items strewn about in the room and some others inside a tomb. Our sorcerer used Detect Magic to know if any of the items was magic, and indeed they were, but we were fearful that they may have any protective enchantment to harm us when we tried to take them, and we couldn’t use Identify since we didn’t have the materials to do so. We discussed the matter with the DM, and by reading the description on both the Spellcraft ability and Detect Magic, he said that there shouldn’t be any way to differentiate both.

Is he right?

P.S.: I know that in the end, what the DM says, goes even if it’s not in the rules, I’m just curious if we were proceeding correctly from a technical standpoint.