This magical belt is covered with wereshark leather. While you wear it, you have advantage on saving throws against being charmed or frightened, and you gain the wereshark's Amphibious and Blood Frenzy traits as well as proficiency with Perception and blindsight out to 30 feet. You also gain a Strength of 18 and a Dexterity of 15 if each score isn't already higher.

Amphibious. You can breathe air and water.

Blood Frenzy. You have advantage on melee attack rolls against any creature that doesn't have all its hit points.

Curse. The belt is cursed, a fact that is revealed only when you attune to it. The identify spell is deceived by the curse and falsely reveals the item to be a Belt of Frost Giant Strength. Attuning to the belt curses you until you are targeted by the remove curse spell or similar magic; if the curse is removed, your attunement to the belt also ends. While cursed, you cannot remove the belt, and you refuse to wear any other belt. You also have vulnerability to bludgeoning, piercing, and slashing damage dealt by attacks using silvered weapons. Finally, during nights when the full moon is out, you experience all the effects of the curse of wereshark lycanthropy following the rules described on page 155 of The Impermissicon, including gaining damage immunities, the shapechanger trait (which absorbs this belt into any forms where it doesn't fit), and the change to your alignment. Your DM is free to decide that this places your character under DM control until the sun rises again. During this period, you are able to pass on the curse of lycanthropy just like a true lycanthrope.

Notes: Set: Dexterity Score, Advantage: Saving Throws, Proficiency: Perception, Sense: Blindsight, Set: Strength Score, Buff, Cursed, Belt