Hmm, what about just saying: "Screw it, i'm going wnb caster!", instead of trying be all like: "Hey, look at me, I'm fighter!".
Assume 18 starting wisdom.
Level 12 - +3 Level bumps to wisdom.
Race: Anthropomorphic Bat - +6 Wisdom.
Items: 88k starting wealth, let's spend 36k to get item of +6 Wisdom.
33 Wisdom and natural flying speed. +11 Modifier means that our save DCs are relatively high. Let's take the following feats: (8 feats total.)
Expanded Knowledge - Ego Whip
Quicken Power
Metapower (Quicken) - Ego Whip
Metapower (Twin) - Ego Whip
Psionic Meditation
Twin Power
Free Action: Quickened Ego Whip, augmented to the max: 3d4 Cha dmg, will half.
Swift Action: Hustle, gain move action, regain focus.
Standard Action: Twinned Ego Whip, augmented to the max: 6d4 Cha dmg, will half.
Move Action: Either fly upwards if it's first round and the target wasn't dazed from the whips, or regain focus.
9d4 cha DMG = 22.5 average, and we spent: 3+11+11=25 power points. We have 109 to spend. We can repeat this total of four times, for total of 90 charisma damage. Even if we assume that the fighter saved against all of them (Save DC 27), he's getting 45 charisma damage, and passing out. Then we poke him full of holes.
Now, I suppose it's fair to assume that this'll get countered by, surprise surprise, undead. No worries here, we have two unspent feats, we just need something that we can replace Ego Whip with..
Expanded Knowledge - Energy Missile
Metapower (Twin) - Energy Missile
While this isn't as awesome.. It still does have certain benefits. First of all: Manifest first one as sonic, aiming four extra missiles to the equipment of the fighter: It'll deal.. 22d6-22 = averagely 55 damage, ignoring hardness. Even assuming that the item makes the saving throw.. 22 damage, it's going to destroy just about anything that isn't larger than normal size. Sunder table shows that Heavy Mace has 20hp, doubled if it's larger, meaning that in two rounds it's still gone, or one assuming that the fighter doesn't save. Fighters are rather poor without their weapons, you know. Same goes for armor, even if adamantine, as I really doubt any kind of armor would be even near 1 inch thick at all spots, and you know, broken armor is useless.
So, we can fairly assume, that unless metagamed against, we can deal 22 damage to the fighter 8 times from the air, and destroy 4 items/round. This means weapon and backup weapons on first round, of course, and armor and stuff on the following ones.