Bonelace Insignia

It's says in the game to double-click it to apply to an item. I have bonelace armor but it won't let me add the insignia to it

If you've bought bonelace armor from an armor crafter, it will already have the bonelace insignia built into it (and you cannot apply another insignia if you want a different bonus on your armor). Insignias only apply to armor crafted in the Nightfall campaign (the continent of Elona).