In a recent post on the official Final Fantasy XV forums, game director Hajime Tabata has has confirmed that the automatic system from the Episode Duscae demo has been removed for the final version of the game.
Originally, the automatic system consisted of different attacks in a combo or outside of a combo with each attack using a different weapon e.g. Crush→Ravage→Vanquish with the weapons Avenger, Blood Sword and Wyvern Lance respectively.
Replacing the old design is a system that enables players to freely switch weapons at any time during attacks. Each of the weapons equipped can be changed in real time using the up, down, left or right directional buttons on the game controller. Tabata notes that this is “normal” in a continuous attack. It also prevents weapons from being automatically changed in unintended timing. This also opens up opportunities of creating combinations of real time weapon switching. In short, players can perform continuous attacks with a different weapon on the fly.
Additionally, for ‘Counter’ attack and ‘Raid’ attack – those attacks will be executed based on the weapon currently being held but players can set a specific weapon to use for those attacks in the customization menu of the game.