Is there a reason he's being vague? Can we press "information is valuable, espically information on warding against a curse that was mighty and terrible even before the Mending. Maybe a full hundredth as valuable as good and honest contextual teachings from a living mind (Valen) or the knowledge that if shit goes bad, you have a method of summoning your terrifying daughter and her equally terrifying friends".
I mean, I see no reason for him to be vague, unless you haven't made a thing for it yet, that's fine. But keeping secrets like that is just... Against the spirit of our approach to magically healing.