Prismatic Helm

 is headgear in. Upon completion of the Trial side-quest, the Rainbow Shell can be forged by Melchior into either three Prism Helms or one Prism Dress. If you have the Sun Stone, then he'll make some PrismSpecs (an accessory that greatly boosts damage).

Prismatic Helm can also be charmed by Ayla from the left hand of Queen Zeal (Boss).

While Prismatic Dress can be equipped only by female characters, Prism Helm can to be equipped to anyone.