Just found another great exploit.
1st, find a piece of gear that boosts memory. Then, after adding a new ability to the bar, unequip the memory item and you will still have access to the ability that you no longer have enough memory for!
You can trade the piece around to have every one of your party members get the benefit.
On my skill panel I see "Memory slots used: 8/5", and can still use all 8 of those abilities.

This is better for full party playthroughs as the temporary gear sharing gets 4x the effect.

Update:
I've observed some really weird behavior the more I've played around with this.
Some steps to help this work:
1. Pull everything from your memorized skill list (to ensure no 'hidden' abilities are in there)
2. Add all skills you're interested in using.
3. Remove memory equipment.
4. If one of your skills was removed after taking the equipment off, remove that skill, add a different one, and start again from step 1.

The skills seem to have some sort of hidden queue for how many extra slots you can have before they get removed. The removal ordering for the skills I know seems to be Crippling Blow -> Battering Ram -> Rage -> Rain. If you know the first 2, and aren't using them, you can get 1 free memory slot, then an additional free slot for each one next in the 'removal list'.
I think this is based on the abilities you have learned, so you may have to learn a few abilities you won't use to make this work.
I'm unsure if there are other abilities that may be lower in the list, it doesn't seem alphabetical, and it isn't how they're ordered in the skill tab either. Of note, it did use all 3 of the warfare skills I had before moving on to a Hydro skill. I don't have enough memory to determine what is next in the list. If I don't use those 4 abilities I can have 8/5 for all my other skills.

Edit: I learned some necromancer abilities, and then I couldn't keep Rage memorized at all w/o full memory. Could still get 8/5 with other skills though.

Last edited by error3; 09/10/16 05:45 PM.