Thanks, and as Rai said, they indeed do spin and there's unfortunately no way to change it ;/
About the weird trajectory I spoke of:
It only appeared when I made a Fuuma Shuriken (those giant, inverted shuriken from Naruto) - you can test the effect by simply doubling the size of this shuriken and test it in Soldat - it will look as if it was a boomerang that keeps changing direction, bit hard to describe ^^
These ordinary small shuriken fly in a nice pretty straight trajectory, although (if you look closely) you can see that it does indeed seem to shift itself slightly up and down during the flight, but its hardly noticeable and I only found out because I was checking for it ^^
Thyr~