It enables you to view enemy skills and item drops during Analysis. (gamecmd.com)
Once appraised, the Grimoire Stones give characters with abilities outside of their pre-set classes, endowing the ability to use different weapons, equipment, or even enemy skills. (tech-gaming.com)
Puzzle & Dragons Z and Super Mario Bros Edition let you utilize enemy skills that charge up after a certain number of turns have passed. (tinygirltinygames.com)