No dismemberment. The amount of force that would be required for even the sharpest blade to slice through bone would be immense. The only way it could be implemented realistically would be if the same area was hacked repeatedly, which would mean dismemberment would be pretty tricky to do on a living target, but I'd rather they just left it out altogether. It's not necessary for realistic combat.
If they are wearing armor, chainmail at the least. Hands, feet, and heads are the easiest to chop off because of the weakness of joints, though feet are less likely because they are away from the action. I've read some accounts of Roman battles that said that their enemies were shell shocked by the gladius, which was able to chop limbs and heads off quite easily. I'm guessing this is because they were sharpened and cared for better than many weapons at the time, and perhaps their shortness allowed them to make quick powerful blows, although generally it is longer, heavier weapons that are better at that sort of thing.
My biggest concern is that it does seem, well, messy. Imagine seeing heads, hands, and fingers rolling around after a battle. Then again, that sounds pretty cool.