User blog comment:KnocknickKnock/Lucy's Unused Power!!!!!!!/@comment-77.194.131.128-20140715085522/@comment-74.61.219.92-20140724182443

It isn't about Increasing her power considering this is stuff she can do now. This is not potential power this is unused power. Lucy throughout this Series has shown she can easily perform Unisons between her and other poeple, Spirits and other people, and Spirits and Spirits. Sagittarius already showed he could use his arrows to combine magic into a large attack during the Daplne arc. Taurus axe already showed it could absorb another spirits magic and create a typhoon or storm with it. Scorpio already showed he could combine his sandbuster with another element to create a more powerful attack. Lucy already Showed she combine her magic with someone elses to create a stronger attack.

Lucy doesn't need to go train or leave the guild to do any of this stuff. All she needs to do is summon the spirits and have them do a combination attack.