You have to research each trait for each item type separately. Opening the research tab, go to the item type you have a trait for. It says "unknown" because you have not yet researched it, but it should be in white color writing instead of greyed out if you have the item in your inventory.
Just double click / activate that trait and a pop up comes up allowing you to select the item you want to research. Confirm, and the research starts.
Just sayin'UltimaJoe777 wrote: »To add to this it will say Research in white instead of Unknown in grey if you have an item of that type with that trait. Researching destroys the item you choose though so keep that in mind!