I love the general idea of the phalanx fighter archetype as a cross between a tank and a lockdown fighter but the only class feature I really like out of it is the 3rd lvl feature Phalanx Fighting that let's you wield polearms one handed. Is there a feat or something that recreates this ability so that I don't have to lose armor training for a bunch of meh abilities with a tower shield?
Not as far as I am aware, although you could put some levels into Titan Mauler barbarian to get the same effect (except for a -2 penalty to do so). Not that bad if you take advantage of rage, I suppose, which might take an Extra Rage feat or two to keep it going all day. It would be a two level dip minimum, and you would get armor training at level 5 then (seems like a good level to consider mithral full plate though).
Unfortunately, this archetype trades away fast movement for a +1 to attack and AC against bigger opponents, so you could not rely upon that to keep you at 30' move in medium armor prior to level 5.
You can take exotic weapon proficiency to wield dwarven waraxes or bastard swords one handed, or Thunder and Fang to wield earthbreakers one handed.
Really the part about phalanx fighters I enjoy the most is the brace as an immediate action ability, as it is the only time I've seen someone successfully brace for charge.
You could always pick up a Sun Blade when you get the cash. That's a greatsword that works like a short sword.
You can take exotic weapon proficiency to wield dwarven waraxes or bastard swords one handed, or Thunder and Fang to wield earthbreakers one handed.
Really the part about phalanx fighters I enjoy the most is the brace as an immediate action ability, as it is the only time I've seen someone successfully brace for charge.
Thunder and Fang lets you wield two Earthbreakers technically as it makes them wieldable as one hand and a bonus if you TWF with a Klar but you don't have too.
Personally, a Meteor Hammer with Titan Maauler is better since you have reach, a shield bonus, and a free hand (or two Meteor Hammers).