Right now, with the way the attributes system work, stacking a specific stat is better than mixing things up, because there are only 5 attributes, and 4 of them really only benefit weapons, unless you have enough points to trigger one of the 6 milestones, which start off with a cost of 50 points.
what if each point in attribute did more than one thing? Or perhaps more attributes to pick from.
examples of ideas:
Maybe add crit increase to dex or energy regen. Strength could increase carry weight and reduce duration of CC and reduce incoming damage.
Intelligence could increase crit damage and reduce chance to be hit by crits.
Focus could increase the effect of Blocking attacks.
Constitution could reduce threat generated or threat gained while a threat stone is worn.
Maybe new attributes could be added for some of these things.