That's about standard for a heavy duty wood processor. There are other blades, lighter, but they're not going to be as efficient.
It'd help if you put in some details about yourself, general fitness, and what your intended use is.
My input is to hold onto it, give it a chance. It actually isn't that exhausting using a kuk, unless you have a heap of chopping to do, and a lighter kuk is just going to make you work harder to achieve the same result.
The AK is one of the best wood processors there is. There are lighter blades, but they're not going to be able to accomplish as much throughput.
E: If all you're looking for is LW/usable, definitely take a look at the BAS line. Solid jack of all trades, packable, and you can swing it all day.