What's the use of some untradable items?

Hi, I wonder what is the use of some untradable unsellable items that can't be worn like the Coral Ring, Coral Armband and Coral Necklace.

Also the proto armor identification key (too damaged to be used.)

Thanks in advance.

Edit: I have found that the coral items are needed for some beast tribe quests. And the key too, for a sylph quest.

Turn in for tribe quests.