Since there's no effect for this hat yet. I have few suggestions in mind! Since it is a slotless hat. This restricted jobs which are able to use it ( won't be able to use 3 kiels ). Therefore, the remaining classes that will probably use it are for farmer, breaker, pally.
Farmer (suggested by shane)
i) Drop usable items such as Steamed Desert Scorpions, Steamed Tongue or Dragon breath cocktail when kill certain type of mobs.
Tanker
i) Max hp + 15%, Immunes to Freeze. Redux 5%.
Breaker
i) All stats + 15, immunes to Freeze. Aspd+5.