As explained by Shurelia, these are miniature versions of the shattered Grathnode Discs that are located near the top of the First Tower of Ar tonelico, so they have their same properties. However, her warning isn't necessarily true: as long as there isn't energy flowing through it, there's no possibility of it causing yet other disaster similar to the Grathnode Inferia if it shatters.
There's no clarification of what the "DH" at the start of the name means, so it could either mean "Detail Hymmno", meaning it was altered through the modification of its D-Waves and H-Waves, or ""Dynamic Hymmno", which means it was altered through the application of Dynamic H-Waves (feelings, songs) upon it.
Trivia[]
This item is also present in Cross Edge as one of the unique ingredients to synthesize the Grand Crown, one of the three possible ultimate armors for Aurica, Misha and Shurelia, although it was renamed to "DH Grathnode Disc". This item can only be found from obtaining one of the in-game titles.