I have arthritis in the hands and working with my shears has gotten difficult t cut with compared to when they are nice and sharpened.
It's probably sacrilegious to mention this here, but have you considered using a rotary knife cutter instead of shears? On the risk of being banned from the forum, I admit I've been using one for many years now with success. It cuts very fast and very accurately and easily manages several layers of winter coat fabric in one go. The blade is small enough for concave curves of the types occurring in garment parts for adults. The cloth is lifted considerably less than with shears during cutting, as the foot of the cutter is only 6 mm high, which greatly contributes to producing two exactly equal parts.
You'll only have to support the weight of the cutter with your hand and guide it, no other muscular effort is required. Mine weighs 860 g, a considerable weight compared to my biggest shears, which weigh in at 520 g, but of course the cutter rests on the cutting table during cutting, the same way as shears do. My cutter is from a period when small large capacity batteries weren't available, so it is mains powered. I'm pretty certain there are modern lighter, cordless models available.