So what is the difference of the three weapon classes?

[FakeSympathy]

My understanding is that dual-wield is for fast attacks, greatsword is for slow and sweeping attacks that deal huge damage, and spears are good for destroying stamina?

[Mike]

From my knowledge due to the skill trees you can kind of tailor each weapon for your own play style. The Greatsword has defensive skills, evasive skills, offensive skills, ...etc so you can play each weapon in different ways.

I mostly focused on the great sword and I expected slow hitting attacks that lead to big damage, but what I got was a stagger machine that allows for all kinds of combo opportunities and it is muhc faster then I expected.

I would say mess around in the skill tree as you can reallocate points as you please to mess around with skill you may want to try. So far I have beat the Demo with a tank/parry based greatsword build, and my 2nd playthrough I want all into stamina, and evasive dodging attacks, so I beat all of the bosses without using parry at all.