Can anyone Raise a Shield?

I have not found any Shield proficiency in the game. Can Wizards carry around a Steel Shield, and get +2 AC out of it?

What is the point of the Shield cantrip then? Twice the AC, same action. You can cast with a shield in your hand.
Sure, you cannot use Shield Block, but the cantrip allows it only once per combat anyway, after which you lose the AC too.