Ignore defensive abilities, they are bad and you do not have the points to spare. Your attribute-splitting idea is atrocious. It will weaken your already poor damage score by lowering your STR to boost INT for absolutely no reason at all. CON is actually not good for a tank character if only because the AI targets the weakest characters first, plus since you're focusing on armor skills, And without points into Memory I can't imagine how you expect to support 4 skill schools.
Maybe eventually get INT up to 14 so you can wear mage armor (for the boosts to magical armor), but probably no more than that. With 4+ skill schools you'll want several points into Memory to actually make use of those skills.
Tanking is really questionable due to the way AI ignores high-armored targets.. His damage will definitely be weaker than Dual-wielding and 2H.
You should absolutely not take a wizard when the rest of your party is physical damage-focused. Your group will be completely ineffective at stripping off magical armor, your Wizard will still be uselessly nibbling away at it up until the moment the target is killed by a physical attack. A summoner/necro would be okay since they can default to wood totems and incarnates and Necro does Physical damage.
