This is an awesome addition, however I think it would be nice to see stack sizes for some other items increased as well.
12 to 99 Magian Weapon Trial items just a few examples:
Uluadashi Fangs
Brareus Helms
Sedna Tusks
Itzpapalotl Scales
etc....
These items can really take up some inventory if you're working on the trials in different steps. Maybe getting items while you're still knocking out NMs.
Just my feedback, keep up the good work guys!