So here I am, at 3:30am and nearly dead on my feet, pondering a Stamina system for US.

So one of them things that seems to make the rounds in arguments is that tai/weapon don't last as long in a fight, all pulling from chakra, no reductors, blah blah blah.

Possible solution: A Stamina system.

Framework:

Techs, depending on their basics and usage and whatnot, use various amounts of Stamina and Chakra. Pure Ninjutsu uses only Chakra, pure Taijutsu used only Stamina. Maybe toss something in a couple physical SCs to allow a "Stamina cost" reduction. Endurance for Tai, Speed for Weaponry, idgaf.

Punch someone in the face like you're dropping a rhino? More stamina intensive.
Punch them with fists of fire? Half and half.
Make a motion with your hand and launch fire at them? More chakra intensive.

Everyone has a certain base Stamina, and base Chakra. Let's say

Chakra: 100
Stamina: 100

Each specialty has a certain modifier effect on each pool, increasing and decreasing totals (Stipulation that teritary specialties work strictly as an increase.

So suppose you have Ninjutsu and Genjutsu. +25% multiplier each on Chakra, -25% each on Stamina. Thus, their pools become:

Chakra: 150
Stamina: 50

Consequently, someone Tai+Weaponry would have the reverse multiplier.

Chakra: 50
Stamina: 150

And someone with Nin+Tai, or Wep+Gen, whatever, would cancel each other out and remain average.

Chakra: 100
Stamina:100