When deciding what kind of armor I wanted to buy during my first visit to the Hall of Heroes, I didn't realize that Wolver armor gave you a sword damage bonus and instead went with Spiral Plate Mail. This might have been a mistake on my part, since before five stars it only defends you against normal damage and it slows your attack speed down, but I want to make the most of it.
Assuming I'm using the Spiral Plate Mail alchemy path as my base (no helmet), what would be the best helmet/armor/shield combination to give me maximum defensive ability?
Defensive capability doesn't really help you. In this game, having great defences will not help you all too much, rather dodging attacks and defending against them with your shield will make you invincible. A good shield and a good head are all you need to be invincible. By going for Spiral Plate, you are losing out on the possibility of getting a different armor that is more helpful in combat, just so you know.