Perhaps once you take Axe Focus 1, you don't get offered Focuses for the other weapons? (Sort of like a railroaded secondary path as a subset of the Warrior class)

I like warrior, particularly for early champions. The +3 attack, and a few levels of lethal, are very effective in the early to mid game.

I like assassin for a damage dealer, and warrior for a tank to equip with armour (the horse is not enough), but only if got Adventurer Boon first. A +1 HP/level would be nice for the warrior path...The skills of Sweep and double strike would be a good add, and fit in the warrior path too...

Defender and Governor...I tried but I don't like for the main purpose of my game. And Mage...only when I have assasins, so rarely I can develop them.

Some of the isolated traits might be scaled, to give more variation...Quick I, II,.. maybe Finesse too, Affinity as was stated,...maybe even adventurer boon to allow the warrior to scale HP...

I think the problem with every path is the trait "tree" is more of a shrubland with the occasional sapling sticking up - in other words, there are far, far too many traits that can possibly come up each level, and few of them lead to anything - and the advanced versions are often rare, so you're less and less likely to get them the more you progress up a given branch. This makes your options at any given level up highly random, and picking the one good trait that shows up doesn't necessarily lead to any further good traits, it could well be a dead end.

Mage, warrior, and defender suffer from this - they each have 2 or 3 unique traits that are good to have, buried in a bunch of mediocre ones. Lethality is great, but I never even knew there were more than 3 levels of it, it just doesn't come up often enough. I can't remember the last time my mage actually got to evoker III + affinity. Defender's stun or +5 defense for the army is amazing, but more often than not I'm stuck choosing between spell resist and immunity to criticals (.. how often do monsters or AIs actually use spells or get any crit chance? Not enough to justify wasting a trait imo). Assassin wins because it has many good traits, you never waste a level.

Now say instead of having, oh, 20 or so traits that could possibly come up, you had 5-10, and each one you picked would branch out to more similar traits - so same number of traits in the end, but fewer choices to start with, and those choices are important as they determine what new traits open up for future levels. Say warrior had exactly two unique traits for the path: lethality and trainer, both common picks you can rely on showing up. Choosing lethality would open up more levels of lethality, weapon specializations, and sweep really should be in there somewhere. Choosing trainer would lead to more supportive skills like stun or +1 initiative for the army. The key being that all these advanced traits should be common, the hard part should be getting all the prerequisites, not praying for the RNG to favor you. Along the way we should change most of the one-off traits that neither require nor lead to anything else - say picking strength could lead to (common) adventurer's boon, now instead of praying for RNG to gift me with +8 hp, I can work towards it through a common but less useful trait.

I think having the path trees listed somewhere in the Hiergamemnon would both alleviate some concerns of early players, as well as highlight the "lack of a 'tree'" as you say.

I've never made a governor. I find no use of them because by late midgame I've built up all of the cities I'll need to steamroll late game. Most of the time I'll ravage a weak AI to get a few good cities that they've built and it will usually give me some good border cities to back up my forward army.

The governor trait can make a difference for me in a newly pacified city or early game when my sov is out adventuring and I don't want to waste build queue time on clerics and bell towers to keep production up in my capital (22% base unrest at low tax setting).  Now if they could get one point a turn while in a city as part of the trait that would solve the whole level up issue.  As for now, i move them out for juicy XP fests like shrills and trolls and then back again.  Tedious perhaps, but i like getting lore master or merchant to go along with the admin bonus.

What would be really fun would be a random one turn to build unit or building from the gov being present.

Or a governor might unlock a craft item ability?  Every 25 turns a new goody pops up for you to equip or sell...

Or maybe a governor could get a unique summoned unit for town sieges:  Governor's Detail  Best armor/weapon with heart of fire, auras of grace, vitality and might and stoneskin  .

Love the idea of cleave for the warrior class.