[quote=@RolePlayerRoxas]
Why is it assumed this spell struck her sword in the first place? It's still a form of auto-hitting.
[/quote]

We'll I suppose that all has to do with what sort of spell it was. Most psychic powers/sorcerous powers in 40k aren't bolts or something similar that can be dodged. It more has to do with the willpower/focus of the caster and in some cases (such as many telepathy school powers) the willpower of a living target