Your feats seem kind of all over the place, and you're putting a ton of resources into DR that isn't going to do all that much when you take the really dangerous hits. As a Fighter, you probably want Iron Will.
If you want a high AC shield fighter with punch, focus on strong Two-Weapon fighting and building up AC.
If you really want to use Stalwart, focus your build on getting Improved Stalwart and using Crane Style. Fighting defensively with Crane and a bit of Acrobatics grants +4 Dodge at -2 attack. Build the whole Crane chain and you get +8 Dodge at -1 attack.
If using a reach polearm, have at least 14 DEX and Combat Reflexes for Attacks of Opportunity. Use Lunge to attack from 10 feet away on your turn. Tripping can work very well with reach weapons, but costs feats to do well. You can make a polearm and shield build with Shield Brace.
Accomplished Sneak Attacker grants more Sneak Attack.
You can't use Slashing Grace with two weapons, sadly. But Ranger Combat Style means you don't need to have high DEX to use TWF anyways.
Instead of two Finesse Wakizashi, consider going strength and using a one-handed sword in one hand and a cestus or spiked gauntlet in the other hand. When using TWF, you attack with the sword and the hand-weapon. But any time you aren't using a TWF full attack, you grip the sword in two hands. Changing grip is a free action, so you get to switch between two-handed and TWF for attacks, which is very strong.
Note that Slayer Study Target is supposed to use a swift action as you go up levels. If you use Mythic Feint, you can't use Study Target unless you use it as a move action. But using Study as a move action ruins your combat for a round.
Mythic Vital Strike is extremely good, you might want to use that one instead with normal feint.
Sure. If you want to use Mythic Vital Strike on a Fighter, I'd also get Greater Trip and Felling Smash. Then you can bash things with Mythic Vital Strike and then knock them down and hit them again.
I don't know how complicated you want to make your build, but there's a million cool things you can do with multiclassing Fighter.
You can make a strong two-handed Fighter with DEX too, if you want.
* What level of point-buy are you working with?
* What sources is the GM allowing?
* Does the GM frown on multiclassing?
* What is the rest of the party looking like?
* A you playing from 1st-level, or parachuting in higher up?