You can't use them in battle and can't carry more than one into a dungeon, so their overall usefulness is limited, but if you find someone out in the field (or Eureka/Bozja) and don't have a way to raise them magically, it can be used in that case.
Printable View
Well, in addition to them being flagged Unique and only usable outside of battle, they can also only be used on party members. That really limits their practical use outside of DDs. Even in Trust dungeons, if the healer somehow dies the other party members will use a PD on them so you don't have to.