Obsidian has an interesting idea about weapon proficiencies:
Number of proficiencies is going to increase with character level and is constant between classes (with one exception). You don't need to pay for them with talents.
It means modals are going to be more common in POE2, especially if enemies use them too.
Sadly, current buff/debuff stacking mechanics are not that well suited for modals. Modals and spells are in the same category and it is a non-stacking one. You may be happy with your +damage - attack speed modal, but the moment your priest buffs you with +damage s