I was also going to suggest a 5 1/2 inch cordless trim saw, but hesitated because mine is so old. I am not sure how it compares in weight to modern circular saws. Cordless trim saws are self-contained and relatively small and lightweight, so they are easy to use. Like @woodnthings
, I have been using a cordless circular trim saw for a very long time. It is the only circular saw I have owned for a very long time, and it just works.
My Craftsman 315.115160 "C3" cordless trim saw is nearly 40 years old. It weighs 6 lb, 6 oz with a thin lithium battery installed, 7 lb (10 ounces more) with the thick battery. Lithium batteries do not weigh much compared with the old NiCd batteries. I wonder whether modern cordless saws weigh less than my old one. I would not hesitate to buy a larger, corded saw if ever I felt the need, but the trim saw does everything I want and more. The odometer probably has several miles of cuts in 3/4 inch plywood, and lots of other lumber as well.
I have used other corded circular saws, including the popular worm drive SkilSaw. The worm drive saws are incredibly powerful and capable. I used one to help a friend build his house. They are great for construction, but overkill for basic home repairs and woodworking. Worm drive saws weigh far too much for our OP, in my opinion.
If it were me, I would look at lightweight cordless and corded saws. Bring a kitchen scale that goes up to 10 pounds. If you are buying a cordless saw, make sure it uses some kind of rechargeable Lithium batteries. I do not know if anyone still makes cordless tools that use NiCd or NiMH batteries, but I would not buy or recommend any of them.
The primary issue with cordless saws is making sure that the battery is ready when you need it. I have two batteries. One battery is thin, the other is thick and has a much higher capacity. Lithium batteries do not weigh much compared with the saw. Battery capacity is another issue. The battery can run out of charge when you are cutting; chargers are fast, but you can out-cut the charger. If you get a cordless saw, consider getting an extra battery for it.
One more comment:
I am reluctant to recommend any Craftsman power tool these days, because ownership and management of the Craftsman brand has changed so much recently and has an uncertain future. There are many other brands of circular saw to choose from, with similar products.
One positive note about Craftsman:
About 20 years ago, Sears/Craftsman released compatible Lithium batteries and a charger that were a direct replacement for the old NiCd batteries. The old NiCd batteries sucked. I would have tossed those tools a long time ago if it were not for the availability of the newer Lithium ion batteries. What a boon! Thank you Sears/Craftsman!!