I think the issue is because you basically made it so theres no real reason to ever go for a Str based samurai over a Dex or Con based one. And the archetype does contain those two types of samurai in abundance.
So what do you propose to do?
The only attacks that target Reflex are area-based damage attacks.
Entangle, grease, web, earthquake, shall I continue?
AC is no real defense. Everybody knows that.
Then by all means remove his armor proficiencies and make him fight in a kimono.
You'll notice I haven't given any initiative-boosting abilities to the samurai. That's because I felt it would be overkill otherwise. It's like giving WIS to all saves on a cleric.
Hey, you gave it 1-scratch-kill attacks, wanted to give it infinite stuns per round, settled for 4 stuns per round, the whole class is screaming overkill as it is.
Battle Grace also helps diminish MAD. Notice how a lot of samurai abilities use the highest of his mental ability scores for DCs and such but they don't directly increase damage (except for Shitou no Hate)? Without Battle Grace, a samurai would need AT LEAST three reasonably high attributes: STR for damage/hit, CON for HP/Fort (and no one EVER neglects CON), DEX if he wants to go the light armor route, and one other that influences pretty much half or more of his class abilities. That's four attributes out of six. Pretty much as MAD as the Paladin (who needs 14 Wis for spells, high Con as a melee type, high Str for damage/hit, and a reasonable Cha for both the face role and saves).
Warblade also needs 4 stats (Str, Dex, Con, Int). Anyone thinks a Warblade sucks around here?
Actualy your samurai wouldn't even care if he was adding +0 to damage from stats, because even if it just inflicts 1d10 damage the oponent is as good as dead, and it can't fight back at all because it's bound to fail one of the four stuns you inflicted on it, bypassing all immunities, remember?
A class doesn't really care that it's MAD when it's geting such overkill abilities.
Oslecamo, you're being awfully confrontative about this. Point by point...
1) Those are impediments, not attacks. Most of them only care if you can attack at range or not. And Earthquake? SERIOUSLY?
2) No. Armored samurai also exist. I've given benefits both for the light/unarmored and the armored version so that neither is shafted.
3) First of all, infinite stuns is ridiculous and you know this. And I never "settled" for anything. I corrected what was an oversight in the first place. Second of all, you have to build up the scratch. If your opponent can't kill you in ten rounds or less, then by all means, it should already be dead anyway. The class is balanced against tiers 1 and 2 (at WORST high tier 3). It's not meant to be balanced against regular beatsticks.
4) The Warblade needs Dex? Where? Plus, maneuvers. Even with relatively low stats, the Warblade can be reasonably effective. Not GOOD, but reasonably effective. Conversely, the Paladin will suck if any of those four stats are low.
5) This is ONE out of three styles. Kindly notice that while it has incredible offense, it has no defensive capabilities and no way to attack at range. He won't be getting four attacks per turn until level 15, by the way, and that's IF he gets a full attack on. At a DC of, say... around 26, MAYBE 28 if he invested in it. Does it seem like a decent melee monster is going to fail all of those?
I think the issue is because you basically made it so theres no real reason to ever go for a Str based samurai over a Dex or Con based one. And the archetype does contain those two types of samurai in abundance.
EDIT: Also giving it straight out "win fight" abilities doesn't really make it a superior class.
It's got a couple of additional options that help though.
No reason not to go the other way, either. I suppose I could make it so he uses the highest of his physical ability mods to determine damage/hit. But one of them just doesn't... match. How do you hit with Con? You flex your health at the enemy?