Telekinetic Boomerang, Kineticist 3, Psychic Warrior 3. Found on Races of the Wild page 176. Specifically states that you can use the weapon again on the same turn after throwing it. Lasts 1 round/level, swift action to manifest. Only affects one weapon per manifestation, plus another weapon per 2 PP it's augmented with. Have your mind-switching Psion cohort manifest it on the blades before you go off.
Note that it actually works on any object, not just weapons. I don't think that matters for this build, but I figure it's worth mentioning anyways.
This is definitely what I was thinking of whenever I thought of Teleporting vs. Returning, seeing as its in the same book as Returning Weapon (Assassin 2, Sor/Wiz 2) which is almost exactly the same, except that it just gives the regular 1 attack/round Returning ability.
Edit: I just thought of something. Could you have your Psion cohort fuse you (with Fusion) to its Psicrystal? I don't really understand how Fusion would work out, but if you keep your mega-whateverpede form and gain the Psicrystal's Self-Propulsion ability, you can sprout some more legs to use.