At the start of the battle when fighting Ithaqua it states 'Investigators must roll a die for every item they have, discarding the item on a failure.

Does that mean I have to roll a dice and if it comes up 5 or 6 i keep it. Otherwise I lose it?

Also what exactly is meant by every item. Does that mean all cards that you have or just certain items?

Thanks guys!!!

Yep. Blessed/Cursed affects the roll and there are some items (Derringer, Deputy's Revolver) that can't be lost. And it's also rolling a die for each item, not say if you have 6 items, rolling 6 dice and then choosing which to keep and discard. Items include Common, Unique, Exhibit Items and Spells. Patrol Wagon and Deputy's Revolver also count, but only the latter is relevant here and can't be lost.