I would add a section for Optional Advanced Play where feats, weapon specialization, focus specialization, and human variant types would be found. I would slightly expand the weapon and focus rules to add a little more variety in choice. Just spit-balling but something like a mistletoe focus would would give a +1 DC to any "plant" spells in their descriptor but a -1 to damage. I like the idea of a fighter drawing a flail, and that means something, and the same goes for a wizard armed with an orb instead of a wand. So a wizard could specialize in casting with a wand, a barbarian could specialize in battle axes, and a bard could specialize in tooting his own horn. It would be like the 1e Unearthed Arcana but expanded to include casters. The Advanced Play would also contain fighting schools, casting schools, and psionics, each using the template found in the latest UA where players can choose a subclass that is tied to a theme rather than a single class.