5% of the time you get 10 Magic Attack Bonus (MAB), so this averages to 3.5 MAB and 3 Magic Accuracy (MACC).
Summary: It's a sidegrade from Oneiros Sash, and lower average damage than Othila Sash/Maniacus. Still, it's easier to obtain and more jobs (BLU in particular) can use it.
This comes from Meeble Burrows, Associate Researcher path for 25,000 points (after completing that rank).