My core.

[Indicating with his hands toward his torso.]

Stomach, chest, head. Stomach is preferable, since the chest is protected and the head is a small target. If you want to do damage, get out of that stance. Fencing is nice, but it's only applicable if you're accurate and have a rapier or some sort of sword like it. Stand with your sword side toward me, feet shoulder width apart. It makes you a smaller target and keeps your weapon between you and me.