PF does not do dex-based warriors well at all.
That said, the only truly effective dex-based warrior I've seen is a
Magus that uses the
Dervish Dance feat and fights with a scimitar. Spellstrike + Spell Combat makes for a brutal full attack, especially once you can use your arcana pool to give the scimitar Keen.
Since you're using only 1 hand as per dervish dance and Magus anyway, a strong option would be to build for the Crane Style feat tree found in
Ultimate Combat. Especially Crane Wing, that is REALLY helpful.
[sblock]Crane Riposte (Combat)
You use your defensive abilities to make overpowering counterattacks.
Prerequisites: Crane Style, Crane Wing, Dodge, Improved Unarmed Strike, base attack bonus +8 or monk level 7th.
Benefit: You take only a –1 penalty on attack rolls for fighting defensively. Whenever you use Crane Wing to deflect an opponent's attack, you can make an attack of opportunity against that opponent after the attack is deflected.
Crane Style (Combat, Style)
Your unarmed fighting techniques blend poise with graceful defense.
Prerequisites: Dodge, Improved Unarmed Strike, base attack bonus +2 or monk level 1st.
Benefit: You take only a –2 penalty on attack rolls for fighting defensively. While using this style and fighting defensively or using the total defense action, you gain an additional +1 dodge bonus to your Armor Class.
Crane Wing (Combat)
You move with the speed and finesse of an avian hunter, your sweeping blocks and graceful motions allowing you to deflect melee attacks with ease.
Prerequisites: Crane Style, Dodge, Improved Unarmed Strike, base attack bonus +5 or monk level 5th.
Benefit: Once per round while using Crane Style, when you have at least one hand free and are either fighting defensively or using the total defense action, you can deflect one melee weapon attack that would normally hit you. You expend no action to deflect the attack, but you must be aware of it and not flat-footed. An attack so deflected deals no damage to you[/sblock]
You could take critical feats later, but I think they're kinda a waste. You want to crit so your spells (Shocking Grasp being your work horse) do MOAR DAMAGE.

Oh, and there's
this spell to really wreck someone's offensive abilities on a crit.