User blog comment:FairyRaven/Fairy Tail Chapter 310: The Country We're In, Review and Commentary/@comment-5201441-20121130195908/@comment-220.255.2.170-20121201052259

With regards to your last question, I suppose Yukino was so confident of beating Kagura (even betting her life on the fight) she thought she didn't have to unleash Pisces's full potential. Pisces got summoned in its true form here only because Yukino wouldn't have been able to defeat Uosuke otherwise (even as Pisces got recalled later, lol).