Couple of questions:
1) Are you looking to build a new system entirely or primarily reskinning DnD with essentially a Hyrule campaign guide with a few minor tweaks and house rules to give it the appropriate flavor for the world?
2) How set are you on making it a D20 based system? As in, are you open to suggestions and ideas regarding other tabletop systems? I'll get back to that in a couple paragraphs most likely, but to state it briefly- I'm not convinced you might not be better off looking to WoD or Shadowrun for a potential guide to dice structure, mostly in the area of accumulated successes/degree of success via dice pools as opposed to single-die boolean success.
So, I like some of what I see, though I'm not 100% sold on the ability scores/stats so far. I think I can understand where
@Jerkchicken was going with the idea of too many stats and the suggestion for a greater focus on derived stats. I also kinda think you've tried to go a bit far with the number of stats. While I like the method thematically, it does feel like some of your stats are somewhat redundant or might be better as derivative stats. For instance, I dunno that I feel like "Psyche" and "Wisdom" as you have made them are really necessary as two different things, with the same applying to "Courage" and "will"- they just feel a little like you were forcing yourself to complete a pattern fist and create balanced mechanics second.
That being said, I have seen systems that have nine base stats before. I brought up WoD because it is a system that has three main categories of attributes, with three different attributed in each. However, they have them all streamlined to follow a particular pattern. They have a mental, physical and social block of stats, each with a power, finesse and defensive based trait which ends up making it mesh fairly well and keep some measure of balance (Intelligence, Wits, Resolve vs. Strength, Dex, Stamina vs. Presence, Manipulation, Composure). In WoD, each individual attribute has an effective equivalent attributes in the other two main categories.
Also, since I know I personally don't really like people picking apart my ideas without offering any potential suggestions for how they might like to see things go, I tried brainstorming up my own potential set of attributes and turning them into a quickly-made picture:
So, as you can see, I basically just used the basic DnD stats and reorganized them. I do think some of their naming and descriptions are problematic and would need to be tweaked, though the essence of their purpose would remain the same. Basically, at each corner I have a sorta "power" stat, if you will- the sort you would likely use when you are actively asserting that part of your personality. At each junction of two pieces of the triforce I put the more "defense"-oriented stats. Then, within each triangle is where I placed all the main derived stats, rather than giving them their own separate stat.
So, base stat summary would be something along the lines of:
Str- (power) Raw physical prowess here. Seems a fairly no-brainer for using brute force.
Cha- (courage) Force of personality/personal character- the primary thing you rely on for inspiring others or other social situations where the means of taking command of the situation isn't just a matter of bashing everyone else over the head.
Int- (wisdom) Aiming for magical talent here, as well as knowledge.
Wis- (junction of courage and wisdom) This feels like it could appropriately function pretty much as in DnD- your resistance against both fear, but also mental-fuckery. It would likely need to be renamed, but the essence still kept the same.
Dex- (junction of wisdom and power) Leaning more towards the reflex angle here, this seems like a good combination of both the quick thinking needed to get out of the way as well as the physical capability to follow through.
Con- (junction of power and courage) There's more to getting back on your feat after you have being smashed to the ground than just not dying (though that is certainly a part of it). It is a combination of being able to take a hit and also the courage to stand back up and and potentially take another.
Then, there are my derived stats suggestions:
Hearts- (str/dex/con)- basically just all your major physical attributes determining your HP.
Magic- (int/wis/dex)- your quick thinking, mental resilience and sheer magical talent giving you a magic meter.
Hero Points- (cha/con/wis)- might wanna retool the hero point system, though overall I think it is pretty neat. These seem like a good resource to have to let your character perform those above-average things that normal non-heroes just don't do on a regular basis. If you are into Shadowrun, this is effectively what they would call "edge", or alternatively the "willpower" mechanic from WoD.
Stamina- Anyone who had done a major exam, run a few miles in gym or given a major presentation in front of a group of people knows that there are a lot of ways to leave yourself completely drained and utterly exhausted. I like to think of stamina as a resource that any sort of activity might potentially deplete, hence why it seems like a great stat to have derived from all three main defensive attributes.
Then, you would also neatly have a "Power", "Wisdom" and "Courage" score, in case the triforce did come up as very relative for determining who would be allocated each piece without having to make all the categories strictly mutually exclusive.
I also do want to comment briefly on attribute numbers. I have always kinda thought that DnD has needlessly inflated numbers when it comes to attributes. Sorta thing I've referred to as "Yugioh syndrome". Basically, in the Yugioh card game, you can categorically cut off the last two zeroes from every card and life total and the game will remain completely unchanged other than the numbers not looking as impressively inflated (card game had been around long enough I'm sure there's a "50" somewhere in the game, but we aren't gunna get pedantic here). Basically, when it comes to attributes in DnD, the number isn't super important- the only thing that really matters is the modifier. Odd numbers might as well not exist for how relevant they are. Basically, if you subtract ten from every attribute, divide by two and round down the game remains unchanged. Your 18str is really a +4str, your 12int is really a +1int. I do realize negative modifiers exist, though realistically they aren't super important and tend to be more of a thing best left in the realm of the minmaxers anyways.
With that in mind, I would have most stats range by default from 1-5, meaning even if you do something like completely dump on all physical attributes, you will always start with three hearts- which just sorta seems right to me for a Zelda game.
Also, I like the idea that there should be more of a focus on getting items, due to the heavy reliance on them to get tasks done throughout the Zelda franchise. To that extent, I might suggest putting a bigger focus on creating/crafting items and having those sort of take the place of where skills would be. For instance, rather than strength plus your ranks in climb, you might be looking to do strength plus the rating of your grappling hook. That seems like it might be a nice middle ground between more traditional DnD mechanics and the traditional Zelda gameplay.
Even if for some off-the-wall reason I decide to still go with something different, your diagram and the functionality here is something I will likely use as a basis.
