First level maneuvers/stances are pretty weak, but there are notable exceptions. Sadly, many of the maneuvers do not work as intended so far (or I tested something wrong).
Well, as a warblade/psion you probably dump wisdom. It means not that great will save. Therefore Moment of Perfect Mind should be good choice, I am not sure how it works now though. Of the first level maneuvers I could recommend Sapphire Nightmare Blade - good low level damage boost. Wolf Fang Strike is good in PnP, attack with both weapons as a standard action, but in NWN - not that great. Charging Minotaur is nice, so can be Stone Bones. I wouldn't recommed steel wind or steely strike. And I don't really remember the level 1 White Raven maneuvers right now.
For stances, Punishing Stance gives great damage boost at the expense of some defense - IMO worth it, Blood in the Water, though impossible to implement perfectly, provides nice bonus to attacks and damage (doesn't stack in the current version though). Bolstering Voice might prove handy if you play in a party. No idea if Leading the Charge works. Hunter's Sense in NWN gives Listen bonus I believe, compared to Scent in PnP. I'd skip it. Strength of Stone is bad, and Stance of Clarity is good against single strong enemy... While usually you fight a lot of mooks, I'd skip it.
