The belt itself emitted a constant spray of "nucleon" jet fuel which propelled Jaguar at high speeds through the air with but a thought. These two jet packs attached to the belt were never used as more than an instrument to achieve thrust and altitude. And to keep his trousers up.
For E-Man, he didn't inherit an ancient energy source.. He WAS the ancient energy source, spawned from a supernova as a sentient life form.
After acquainting himself with material life forms he discovered on Sirius IV, he eventually came to Earth and formed a replica of a human body. At which point he adopted the alias of Alec Tronn, named by a very important woman in his life (more on her later).
Among his abilities was the aforementioned shape changing, which allowed him to adopt a variety of forms. He had a pre-disposition towards animals, for some reason. And rockets, which he used to jet his body through the sky. He also projected energy blast from his hands with varying results against his variousf foes.