I can see your concerns with regard to the craving and will adjust it according to your suggestion. Thinking over it I concur that the possibility to shift focus might be very benificial on the long run. Also, as a spontaneous idea, a general craving for knowledge could also include a certain greed for items that are said to hold knowledge or at least to be a great mystery whose solution would be some kind of feat. This could add more concrete targets to Athanar's repertoire as, as far as I understood it, Rheniam certainly doesn't lack artifacts and magical items of great value with associated rumors and stories.

Actually I think that Newton's second law doesn't need to be a disadvantage in all circumstances. When I designed the spell I also thought about potential applications such as boosting the height of a leap by giving the ground a blast of this ability directed downwards, propelling Athanar upwards like the brief ignition of a virtual rocket engine. This wouldn't be possible without Newton's second law. But still it primarily serves as a limiter to the scope of this ability since I thought it might be too powerful otherwise. And it gives potential to grow, quite literally, since any increase in Athanar's size and weight only increases the threshold that will blast himself off his feet or overburden him.