You can't reforge armor, sadly. I have the 27 Light Chest and I can wear full Iron Banner armor with an Exotic Helmet, which I have on my Titan as we speak. Both of those facts kind of punch holes in your statements. If you have indeed obtained Silimar's Wrath, I'd greatly appreciate it if you would equip it on one of your three characters so I can check it out for myself, as this is the first I've heard of anyone obtaining it.