If I take Lasher as a PrC, I won't really need a Whip Dagger, because Lasher allows damage done by a whip to be either lethal or non-lethal, player's choice.

I'm thinking of dipping enough into lasher to get the 3d6 sneak damage, which would class out as Ranger 5, Lasher 9. So I need 6 more levels of something good, and that Psychic Warrior/Pyrokineticist combo sounds pretty awesome. what would I have to level out in my final 6 to get that done? Or do I need to start earlier and finish out with more levels of Lasher?