Extreme Speed, Grand Destroyer, Damage Up, Almighty Power. You can buy all of them from Spica. Alternative ways of getting them are by Recrystallizing the Zetsuei & Zanmu, Fever Modar, Sharkgill, and Ar tonelico? items, respectively.
Tofu Armor, Foam Weapon, X Irresistable, Energy Drain, Cosmo Diamond, and Forbidden Melody are some Grathnodes hat work well. You can also buy them from Spica or respectively, Recrystallize the Ariel Cage, Neo Hitlezz, Element Spear, Symphonic Synapse, Eversong items.
Those are just some. Spica has a lot more to offer; you just need to check in with her as the items she has on sale changes everytime you battle baddies.
Eoria's Serenade - From a Recipe Card in Tenba Labs, inside one of the 3 heavy doors that are very hard to destroy. Guardian of Elemia - Inside a treasure chest in the Silver Horn Ocarina of Heaven - Complete Misha's Level E Cosmosphere and rest. Sky's Musical Box - Complete Aurica's Level E Cosmosphere and rest. Ring of Aria - Complete Shurelia's Level 5 Binary Field and rest. Doomslayer - Inside a treasure chest in Silver Horn. Vahstrad - In a treasure chest in Dragon's Nest Forest J's Agony - In a treasure chest in the Plasma Bell
Grand Crown - In a chest in Dragon's Nest Forest Operetta - Recrystallize Ar Tonelicard SP G