One level of Psi Warrior doesn't do much with Expansion. At manifester level 1, it has a one-round duration -- just enough to give you -2 AC on your opponent's next attacks, then it wears off just before your turn.
If you're gonna go psionic, go Psi Warrior all the way. Power Attack and the Deep Impact feat work well together, but ya gotta have that BAB +5, so you're out of luck at 5th level. It might be good to plan for that as your level 6 feat.
You could do Weapon Specialization (Claws) then use your psi powers to manifest the various forms of claws. Much fun.
On the non-psionc side, the traditional spiked chain fighter is pretty good. Human fighter all the way, maybe one level of Barbarian. Combat Reflexes, Exotic WP (Spiked Chain), Combat Expertise, Improved Trip, Weapon Specialization, Power Attack, Weapon Focus (Spiked Chain).
The dwarven tin can is mighty fine, too. Fighter 5. Power Attack, Weapon Focus (Greatsword), Cleave, Weapon Specialization (Greatsword), Dodge. Adamantine Full Plate (10,500 gp and well worth every copper). +1 Animated Heavy Steel Shield (9,170 gp).
Don't just be 5th level. Be 5th level on your way to something else. Have a plan for your future. Set up your build for your next 15 levels. This might indicate that you need some sub-optimal feats and skills for the first five levels.
