[Endoperez]

If the icon is seen, the effect is on. The luck effects from Pendant and Coin are both always on. I don't think there are different chances in luck, it's just a 50% (I think) possibility of avoiding damage. It might affect disease-inflicted damage too, but nothing otherwise. The damage received and max hitpoints determine the chance of affliction, it might be as simple as (received damage)/(max hp) = chance of affliction. Regeneration helps against afflictions, besides healing.