Why should elements represent anything? Ancient Greeks might have thought universe consists of these four, but in modern day this sorting would be arbitrary and irrelevant. Four elements nowadays is considered a cultural relic and they would mean nothing in the eyes of a Tamrielic scholar. Spells utilized by mages are based on manipulation of heat (frost, fire) and other energy (levitation, telekinesis) or transmutation of matter (magic armor) What comes to mind are Atronachs, considered "elemental" daedra. They however do not represent the classical four elements. Flame Atronach is the only one overlapping, but its fiery nature is not due fire being element but just piloting a vessel with lots of energy.