Nice work. I hope devs will take a look at this at some point. It would be sad to make such a developed system in your head only to be dissapointed later. I think most of your suggestions are valid. It would be great if devs took some inspirations from you - and it's less work for them! That's basically a win-win!
And if not, modding abilities in seems possible, so I guess somebody could mod them in. I don't think they would be hard to code in and we could reuse some icons used in the game.
However, there are some things that I don't like:
- hard scaling with stats, balancing game about certain ability: Double Grip, Serpent Strikes. I think all options should be viable without passives, with passive working as slight upgrade, and I don't think solutions to weak two-handed/small weapons problems is adding a talent for them. And scaling abilities directly with stats doesn't seem in line with PoE design principles.
- bonus spellcasts for high-level abilities - I don't think giving access to spamming high level spells per encounter is a good idea. It would allow to cheese some fights and render low-level spells useless, as you would never use them having better options
As i see it, we definitely need more interesting passive options to customize your character - and we also need a system to encourage taking them. Right now, when all abilities draw from the same skillpoints pool active abilities and their upgrades are just more interesting, give you more flexibility and more power, especially in short fights, and especially for spellcasters. I would really like "talent" pool restored in PoE 2, making two separate skillpoints pools - one with active abilities and some class specific passive abilities, and one with general passive abilities and some class specific one. I think I understand why they were merged into one - with new skill and weapon proficiency systems devs could be afraid that it will overcomplicate stuff, but most talents are too bland to compete with class abilities at their own. With seperate pool however they could be fine addition.
That said, abilities ideas. I'm not going to bother with cool names. Some of them may repeat yours, if I have some changes in mind. Most of them were inspired by D&D... But so was Pillars of Eternity.
Weapon Focus
2 or 3 or 4 PL, General
DESCRIPTION: Bonus to accuracy with proficient weapons
WHY: To let characters to specialize in certain weapons and gain bonuses using them. Encouraging roleplaying. I don't think you should be able to pick it on PL 1, as bonus flat accuracy could be too powerful so early.
Bonus Spells (I-IV)
PL 2-5, Wizard, Priest, Druid
DESCRIPTON: Just guess
WHY: Spellcasters could use more low-level spells per encounter and it could give them way to buy useful passive abilities on early levels. I think PoE 1 model was near perfect, as I liked one PL delay before you could take this ability and I don't think you should be able to spam high-level spells with that
Spell Focus (Enchantment, Evocation, etc.)
2 or 3 or 4 PL, Wizard
DESCRIPTION: grant increased accuracy and duration with spells of chosen school
WHY: Spellcasters could use more useful passive abilities on early levels, helps focusing on chosen school. I think it should stay nice and simple, and more unique bonuses should go to specialist wizard classes, that should be buffed. Also it could help utilize new keywords system, which doesn't seem to give you many ways to play around except specialist wizards and some unique items. And it could let wizards specialize in some area.
Cipher Focus (Deception, Echo, Shred)
MID PL, Cipher
DESCRIPTION: grant some unique bonuses, cool mechanics when using powers of certain class. I have some ideas. I think it should be more unique than spell focus, as 2/3 cipher subclasses don't give you new mechanics associated with keywords
WHY: New keywords system doesn't give you many ways to play around it. It could help make more interesting and unique builds. And it could let ciphers specialize in some area.
Druid Focus (Decay, Elements, Rejuvenation, etc.)
2 or 3 or 4 PL, Druid
DESCRIPTION: grant increased accuracy and duration with spells using chosen keyword
WHY: As before. New keywords system doesn't give you many ways to play around it. It could help make more interesting and unique builds. And it could let druids specialize in some area.
Priest Focus (Condemnation, Protection, Inspiration, etc.)
2 or 3 or 4 PL, Priest
DESCRIPTION: grant increased accuracy and duration with spells using chosen keyword
WHY: As before. New keywords system doesn't give you many ways to play around it. It could help make more interesting and unique builds. And it could let priests specialize in some area.
Lingering Chant
MID PL, Chanter
DESCRIPTION: prolongs chant linger
WHY: Chanters don't have much class specific talents.
Fast Chanting
MID PL, Chanter
DESCRIPTION: hastens chanting
WHY: Chanters don't have much class specific talents.
Bonus Power Pool
MID PL, Warrior, Barbarian, Ranger, Paladin, Monk, Rogue
DESCRIPTION: Grants +2 power pool
WHY: Non-spellcasters suffer from not having enough power pool points to utilize their abilities later on.
Basic and boring ablities, but I think we need some basic stuff before we start thinking about more wild ones. I think we need more options to customize and specialize your character in Deadfire, and it could certainly help.