It is quite a tricky question but lets see :
see:
overall undead monsters are weak to holy damage
Fire monsters are week to ice
Energy monsters are week to earth
Water monsters are week to energy
Ice monsters are weak to fire damage
i dont remmember I don't remember any holy monster, but i supose monster but I suppose death and holy give increase amount damage to each others, remmember some monsters dont have weakeness others. Remember some monsters don't have weakness even having the determined elemental, elemental but you already have some idea like this.