In the demo you could attack by both pressing or holding down the attack button, this hasnt changed with the new manual weapon switching.
That's about my main worry regarding the combat system now, tbh. The rest look pretty good: if they get the important parts right, it could be a great combat system.
I can't wait for them to show a battle with the whole system implemented: the TGS tech demo looked very good already, as well as faster and more fun-looking than the more grounded and lacking in features Duscae one. Also, summons and magic: hopefully, the latter is a big part of the combat, as it should and seems to be.