I'd just say that you could pick shield proficiency as one of your four weapon picks. Between the characters who already have shield proficiency from class (which includes pretty much everybody who would Strength to begin with) and the characters to whom Moderately Armored would be a superior option to grab shield proficiency, a wizard or sorcerer wanting to drop a whole ASI into being able to use shields might as well get a few melee weapons too to enable their warmage concept.