final fantasy XIII:LR questions (and spoiler)

Hikaruu

First off, i finally beat Bhunivelze. First kill, i got Double Diety, and after reading about some people trying 20+ times, i was excited. Then i looked @ stats. It's obviously crap for staggering or melee damage (idk if the stats change at all when upgraded? (if it can be)) so is this purely a magic dps weapon for after trash / after a boss is already staggered?

 

Also had some thoughts on the ending. Seeing as FF15 (originally versus13) was supposed to be part of the Nova Chrystalis series, in same universe as 13, anyone else think the new world (earth-like) that was created might be the one that FF15 takes place on?