So in tri-stat your three stats are body, mind, soul; the way I'm imagining the renaming is that you got wisdom=mind, power=body, and courage=soul. Each stat governs multiple aspects but it is explicitly folded into just one stat, this does not mean you cannot represent being bad in a certain aspect under a stat. There's a defect to represent a weakness in a certain area and it gives either a -3 or -6 to rolls depending on severity.

Now for combat, you have two stats one for attacking & one for defense. They're both taking the average of the stats, but defense subtracts two from it. Combat consists of three steps: a to-hit roll using the attack and any modifiers, an identical defense roll if it lands, and a roll to see how much damage they receive. There's no real difference between being a blink-tank vs tankyness outside of the presumption that tanky character is gonna have damage reduction. 

Damage has a max value which calculated by adding the weapon base & appropriate mods. The rolling determines the increment taken. It's all in quarters so depending on the result you can do all of it or a minimum of a quarter (you round up when given fraction).  If it's too fiddly for you, an alternative rule is just have everyone do max damage.

Like most rulesets it has abstracted health. With regards to doing stamina & magic it's trickier as there's an option to enable a meter to be consumed for abilities but it doesn't differentiate if it's like stamina or magic. So I dunno, I guess you can make a different meter but keying off to another set of stats?

Anyway the game is quite open to giving powers and stuff via "Attributes" which are just a variety of effects from like simple stuff like armor to stuff like transformation. Since this is Zelda based I'm gonna say that players should be limited especially with like more exotic stuff as that should be handled via "Items of Power" which is how you build equipment that gives abilities. 

Like a hookshot would be an item of power that lets you move around in a special manner and whose combat usage would be something that either stuns and or like moves your or enemies closer.