Cited and translated from the discussion reddit:

In the interview with YoshiP on 6.4 from GameWatch/Famitsu/4Gamer/DengekiOnline:

Q: Mandaville Weapon has progressed in the form of consuming Allagan tomestones and exchanging necessary items in both stages so far, but will patch 6.45 follow the same flow? Or will it be a new process?

Yoshi: I don't really want to say "This is what needs to be collected" before the implementation, so let me refrain from talking about it (laughs). However, in terms of the flow, the intention this time is for players to be able to upgrade (the weapon) while playing various contents at the same time, so please be assured that there will be no major changes.

https://dengekionline.com/articles/183539/