I'm pretty sure that I have read 3e stats for the chakram somewhere, in one of the splat books maybe, possibly OA. Don;t have them available at the moment, so i can't check.
As for the knife, looks good, but why a x3 crit on it? A dagger has a 19-20 / x2 when thrown, and that is a very similar weapon to a throwing knife, so I would go with a 19-20 / x2 myself for it's crit.