I dont see it being a problem with being used in a Null Psionics field. Infact if i recall correctly, Bladeskills themselves are considered to be Extraordinary. That is not to say that you can always use them in Null Psionics Field, as for example, You lose Psychic Strike in a Null Psionics Field, and you might lose you mind blade aswell. But you dont lose access to bladeskills just because you are in a null psionics field.