Fate can fit into lots of realms. Hermaeus Mora deals in knowledge, so he no doubt knows the fate of most mortals; that is to say, he isn't in the business of altering it, just knowing it and possibly sharing the knowledge.
Other deities can interfere with fate in their own way, too. It's kind of a vague word. --- Sometimes I edit my sig so it continues whatever I was posting about.
So is knowledge though. Knowledge is a vague construct. Knowledge of what exactly. Are we talking science or philosophy? For example Azura clearly has knowledge of the future, as evidenced by her gifts of phrophecy given since at least Morrowind (sorry, haven't experienced previous TES installments). So in a way you could say her sphere is also knowledge. Clavicus Vile can pretty much do anything, and I don't imagine him turning down trading knowledge for a few souls, so you could say knowledge is also Clavicus's sphere. Also ALL daedra seem to be willing to swap stuff for favours, worship, or souls, overlapping with Clavicus's sphere.
This could imply that the Daedra are not as powerful as they claim to be, and one will be quick to claim mastery of another's sphere. Conversely they could also be more powerful than they claim. For example a swordsman in skyrim might still have a high restoration skill. Or it could just be sloppy writing. Given the number of people who have had their hands in working on TES I'm assuming sloppy writing, it's almost unavoidable when you try to put everything on the scale of gods.
The discussion of the Skall's religious beliefs also brings up an interesting point. How on earth did the Skall become monotheistic when every other known culture in the world shares the same religion, and worships the same gods, with the same attributes. These Gods even show themselves every thousand years or so. I wonder, was this how ancient people viewed the world? Is this how extremely religious people view the world today? --- Gold Guns in MW3: All of Them