Here are my thoughts on the job "SENTINEL."
The job is a low health, mind focus, barrier Tank. The Tank uses spells like barrier or reflect to block attacks. The pets are fallen soldiers who wishes to still fight for the land even after death. Summon 1 is a Lancer/sword and shield mostly focus on more defensive abilities that protect the tank by absorbing a small portion of damage that was taken by the Tank. Summon 2 is a great sword wielding pet that focus on doing damage.
I think Arcanist is the perfect class to be the jack of all trades. What do you guys think?