Tabata confirmed on the official forums how the manual weapon switching will now take place over the automatic switching that was used in Episode Duscae.
You will have four weapons to chose from at a given time, you will be able to swap these out for alternative options in some manor, however, instead of having these weapons assigned to arbitrary conditions like opening finisher they will be mapped to each direction on the d-pad.
This change means you are in complete control of what weapon you use at any given time. One of my major problems with the auto switching was feeling like certain slots were just useless. Many fans expressed just wanting to have various slots filled by the same weapon, this is an extension of that and then some giving you complete control over the weapons you have set to change between.
This also means instead of switching through a wheel of abilities you can just change to the weapon with the ability you want to use and activate it which will feel much more intuitive than having to look in the corner of the screen just to see what ability you want to use. The information will likely be there still for display purposes, but players who can remember their weapon slots won't need to and can focus on the combat.
A greatly welcomed change from me for sure, I actually envisioned the system to work just like this having all four of the directions function to swap weapons and I'm glad my predictions came true.
Tabata also mentions the two other slots that actually mattered, counter and the aerial weapon will use the currently held weapon, but I believe you can chose to override that with a setting as well.
All of this still needs to be seen in action, there are plenty of other combat related features yet to be explored like aerial combat as well as the completion of the alternate combo strings based on directional input that was slightly added in 2.0. Combat is shaping up to be a lot better already, now if only we could get rid of the QTEs...!
You can see the Tweet from the Japanese Twitter, as well as the forum post linked there over here:
https://twitter.com/ffxvjp/status/649210166907269120