Must stare intently and directly at the subject

page 54 of GURPS Psionic Powers used on TK Crush which has No Signature.
That has Malediction so perhaps that is only available for Maledictions, since Maledictions do not necessarily require a line of sight to the target.
It might make sense for other Innate Attacks too, since you can in theory "fire blind" at people you can't see, like shooting behind without turning around, eyes closed, invisible foes, foes behind cover.
This nuisance effect is however a smaller discount than getting Sense-Based (Reversed)
Category:Nuisance Effects