From memory, there are about 4-5 different ways that Nova/Nova's can absorb or manipulate energy. Keep in mind that a vital part of energy absorption for a Nova Prime is compatiblity. They can absorb ANY form of energy, but some exotic types can cause a massive feed back so they have to be careful. Also, the absorption power is dynamic in that the more energy an opponent puts into an attack, the easier it is for a Nova syphon to absorb, amp and redirect.
1) The most basic form of energy absorption a Nova can do is the classic absorb and redirect as seen here:
When you think about it, even though its basic, its easily used in a combat situation in real time and it can phuck people up.
Another use is a direct leech to amp their own physical stats or to recover quickly from injury. They can do it to humans or to machines as well. All that's needed is direct contact. Once contact is made they can keep on leeching even from a distance. Powerhouse was the best at this imo.
Now look how Nova (who's really skilled with his powers at this point in his career) uses the same type of energy leech technique that Saal used on him. He makes contact, then dances around a bit...
Nova is not your regular "class 100" brick. He is more in the lines of a Silver Surfer who we know is class 100, but rarely ever shows it. For some reason he doesn't get the kind or respect others get for his strength. Here's a small collection of strength feats that may shed some light in this situation. I didn't include punching or ramming strength since being the human rocket and all, that's what he's always shown doing. There are too many examples of that already.
Takes a deep slash across the torso from Badd Axe no worse for the wear. The axe was forged by the Olympian god Hephaestus, presumably out of adamantine.