Once you have the Heavy Armor Schematic (for example, the Warden Heavy Armor), you will need several items. The first and foremost thing you’ll need for your Mage and Rogues to wear heavy armor is a schematic of any one of the armors.
However, there is a little trick to this that you will have to be aware of. Well, there is a way for them Mages and Rogues to actually get their hands on heavy armor that they could wear. You’re probably drooling over some of those cool-looking heavy armors in Dragon Age Inquisition which the likes of Casssandra and Blackwall are wearing, wishing your skinny Mage could also be suited in similar shiny heavy metal.