Right then, the power of Ham and Unusual Cheese Biscuits upon me, onward to at least some of the classes with the rest (moreso Magical classes) hopefully reckoned out here tomorrow as the night is wearing on.
Barbarian:-Thinking behind only 4 available weapon proficiencies out of the lot unless I'm misreading it? I can see how Bows would be less sensible to an extent but that still leaves a sizable number of groups...
-Rage mechanic looks interesting, though I wonder how high level ones will remain viable versus the likes of Waves of Exhaustion and such should that ultimately work out about the same, though I also suppose that would be where teamwork in a party's composition would be key alongside making spellcasters the utmost priority.
-Tangentially related, I'm somewhat surprised there's no relevant Anti-Magic and/or Anti-Outsider practical aspects built into the class outright.
-I assume that a Barbarian with the Tireless Rage feat is still unable to Rage from a Fatigued state? I could kind of see that being allowed though, as progression wise it would serve to make a higher level one more dangerous as Fatigue infliction wouldn't be enough to shut one down from the primary ability.
Bard:-Replace all instances of "her" in the Bard description with "their"---as I'm strongly guessing it isn't a Female Exclusive class. Wacky OGL guide thing from months ago with their gender pronoun weirdnesses.

Or just "A Bard can use music"...."They can also harm" In general, it'd be best for all class descriptions to be gender neutral in similar regards.
-Bit of a disconnect with the Bard having a Counterspell capability in the from of Countersong versus the Spell Schools section saying only Wizard, Sorcerer, Druid, and Cleric can manage any Countering.
-Same unclear 4 weapon proficiency issue as Barbarian---seems to be a running point with all classes?
-Damage progression for Pipes of Pain seems to peter out awful early in the character's advancement---would like to see it continue to scale up into the higher Bard levels to keep pace better, or at least gain some ancillary nifty bits like Deafness inflicting and so on. In fact, I'd say the latter is a much more interesting function for the Improved Pipes feat while the damage can just progress itself with higher level for "free".
Death Knight:-This is the first class I would say that largely falls...flat....or at least strikes as not having enough delineation within itself and versus, say, a Paladin which is the common analog by all indications (Or perhaps the intent was moreso Paladin/Rogue?).
It is probably a given, but somehow, i can't help but see this through a prism of a "Batman in the land of D&D"----just kinda jumps out readily like that.
I'll try to point to as much as I can:
-The Sneak Attacks, Dodge, Swiftness, Improved Flanking, Smite----those seem OK in general and fit well, though the Swiftness feat seems to come awful late in life for what bonus it brings to the table.
-Dark Blessing seems especially vanilla with no progression at all beyond the initial +1, same case with Aura of Dread really although I'm fine with multiples not stacking.
-Not so much a problem, but Smite might be niftier if there was also some chance in an either/or fashion for knockback/knockdown alongside the damage while seeming in character.
-Feat progression peters out rather quickly, perhaps something like Bleed condition causing and other "destructive" things are in order?
-It would really seem like you could make a pair of classes, or at least a factional divide somewhat like my suggestion in the Monk quick poll, between Good/Neutral and Evil in terms of the Feats/Abilities. As it currently stands, there's little "tension" from either vantage point/many stated features versus, say, how the Bard is relatively filled out. The Dark Blessing "makes sense" moreso, as it is written, for a Death Knight under an Evil patronage, whereas Aura of Dread makes sense in general either way as a kind of universal/localized Fear/Intimidation Effect. Making it into a Dark Paladin outright doesn't seem like it would work as the Rogue, from my first reading, seems to already have the whole "sinister magic to complement physical doings" angle down.
-So yes, ideally I'd say this one stands to have more time in the oven to a 2 choice internal bit with alignment determining the pool of feats/abilities with BaB and such remaining unchanged. Failing that, I'd say it'd come down to buffing up and expanding upon things as they currently stand as referenced above. For some details...hmm....off the top:
-Name change Dark Blessing to something that could moreso go either way---like "Emboldened Conviction" or some such as that fits in much better with the profile's mention of commitment to ideals and whatnot. Also, buff it logically as the character gains levels and also apply to to competence checks----perhaps capping it out at +3 at high level?
-Aura of Dread could do with a creeping range boost and a slower creeping increase to the penalty...or at least the penalty increase on top of interfering with the likes of Spellcasting.
-It feels like some manner of class-gained semi-Passive Concealment with fit well thematically with the whole driven, intimidating, combatant. Perhaps....passive Concealment until striking a foe? Hard to say, but somehow it just seems ripe for another power.
Hoping to see other people weigh in on this especially as it is probably one of those things where some obvious stuff is escaping me.
Fighter:-I like the Int modified weapon focus aspect, as it somewhat fits in as a better part of the puzzle versus how the other classes differ. Still reckoning it a bit of a headscratcher for the other classes though.
-Quite like the Shake it Off series in general!
-Being a Feat Machine seems to be a decent enough balance for the lack of Abilities outright. Though, I would've guessed there'd be some Sunder/Disarm action afoot given the explicit and all-consuming Weaponry focus and would say there probably should be such worked into the mix.
Monk:-Heh, while I won't beat a dead horse
too savagely, I still do lobby with zeal for the likes of things I mentioned awhile back in the other topic in terms of specialized Grappling actions (Fish-hooking for Silence, Ear-boxing to Deafen, etc) and such to be implemented to further flesh out the class----Sleeper hold being a good start!
-All else looks good and fleshed out at this junction, aside from the quick poll issue.