“[Luke] is basically tailoring this projection to have maximum effect on Kylo,” Johnson explained. “He knows that Kylo’s Achilles heel is his rage, and so that’s why he kind of makes himself look younger, the way Kylo would’ve last seen him in their confrontation at the temple, and that’s why he decided to bring Kylo’s grandfather’s lightsaber down there – the lightsaber that Kylo screamed at Rey, ‘that’s mine, that belongs to me.’” As far as Johnson’s concerned, Luke believes that Anakin’s lightsaber will have a much more visceral impact on the erstwhile Ben Solo than Luke’s own green blade.
This is exactly what I’m talking about.