In Evil Dead 2: Dead By Dawn, Ash is freed from possession by a kandarian demon by the light of dawn. It is also shown that the demons come out at night.
This idea is consistent with most of what we see in Evil Dead: Army of Darkness, as Ash has to seek shelter in the windmill as night falls, and the army of the dead attacks at night.
Yet at the end of Evil Dead 2 (and at the beginning of Army of Darkness), after Ash is sucked through the vortex, he finds himself surrounded by medieval soldiers, and shoots an attacking kandarian demon out of the air in broad daylight.
Later on in Army of Darkness, Ash is thrown into the Pit, where he fights multiple kandarian demons during the day (and one of them climbs out of the Pit into the sunlight).
What protection does sunlight offer? Why did dawn free Ash from possession, and keep the Evil Dead at bay, but still allow some kandarian demons to act apparently freely?