I've been hyper busy with college work, hell week, and finals week (at least at my college, the week before finals is generally worse than finals themselves) and (sadly) playing catchup in some classes. C is a hard language to code in, and I still am not great at it. So I have not read any of the thread since the update, so I don't know what is/has being discussed/shot down.
So, here's my thoughts on the Boon, with that caveat. I think its probably the most valuable thing we "own" (save
maybe our great deed), and I definitely fall into the "mustn't be too hasty" group with this sort of thing. We should spend a lot of time developing what we want to do with it before we go about doing it, outside and, if needed, inside the story, before we spend it. I'll admit the great library idea appeals (partially just because I
LOVE books and libraries, and want our own Library of Alexandria), but again: mustn't be too hasty. This sort of a Boon is a once-in-a-lifetime sort of thing, and its something I, for one, do not want to use only to say "damn, wish we had that Boon still" and regret our decision.
One possible thing for if Mathilde dies with the Boon unused, is to (in her will) ask Belegar to ensure that somedwarf (maybe get Gunnars or his colleagues in on it) to take guardianship of the Liber Mortis, with the description of its contents, and to judge if an undead disaster is big enough for someone to be allowed to look at it. Having it in the keeping of the Dwarves could well be a very good idea, as they can hold the knowledge within without being tempted to use it. (Because they can't, as far as the dangerous stuff goes.)
I think this is a really lovely idea that fits really well, but would probably mostly be just fluff because... ya'know, if she dies, that's it, that's the quest. If course, might not be, if its a "mysterious disappearance, presumed dead but actually not"-type thing. No idea how that'd happen, but I could see it. It's a good contingency plan. The dwarves are about as good a keepers for that book get, save probably the Slann that Math really doesn't know anything about.