The Hollow Helm is a shiny metal helmet that must be worn in order to activate its feature.

Unsettling Presence. Once the command word is spoken, as an action, you can unsettle a creature you can see within 15 feet of you. The target has disadvantage on the next saving throw it makes within the next minute. Constructs, undead, and creatures that can't be frightened are immune to this feature.
There are three charges on this helm, once you use this feature three times in one day,  you can't use it again until you finish a long rest.

+1AC. This helmet gives the wearer a boost of +1 to their armor class while wearing it.

Notes: Bonus: Armor Class, Fighter