noob Q.
how to get legend spheres ah ? or legend materia ?
Must fully dive the character's record sphere to unlock its legend spheres. Then dive through their legend spheres to unlock legend materias.
Alternatively, some relics provide Legend Materias upon equipping or mastering it. In such cases, you don't need to unlock their legend spheres to do so (but only can use that particular Legend Materia).
Need 5* motes to Legend Dive ..