Only magical items have magical properties, so you go through the items trying to identify properties until you find an item that qualifies. After you've found one, then the next party memebr can do the same to the rest of the items.
This is questionable.
The rules do not state one way or the other, but the rules do state how to detect a magical item.
So, I think the burden of proof is on the side that claims that you can handle an item and instantly know that it is NOT magical (and hence by default, quickly search through the 47 swords to find a magical one).
In the case of the 47 swords, which one is magical? Either Detect Magic points it out, or the DM is generous and tells his players which are and which are not, or x number of short rests go by (~5 short rests max at 5 minutes per short rest, 5 PCs, and a few minutes per handling of each of the 47 items) until one of the PCs finds it.