A Tank needs two primary attributes: STR and CON, with maybe some SPD for mobility. If you're putting in so many points into CON that you're unable to equip armour that you need, perhaps your build needs to be balanced better. You can focus yes, but going 10 CON 5 STR at level 1 is not going to be ideal.
Shield specialization is indeed pretty weak-looking right now. Maybe points in it could grant special defensive skills, like Bash, Taunt, Impenetrable Defense, and others.
