Well, I'm surprized that the old pair didn't show up 15 minutes after you brought the replacement pair into the house. that's what always happens to me! I was wondering if you had the old pair for a very long time and had them sharpened a lot if that didn't reduce the weight.
I do know what you mean about an extension of your arm. I have an old KAI teal and purple rotary cutter from the 80s or 90s. I LOVE it, but there was a plastic thing-y where the center of the blade goes that finally wore out. I brought it to the last sewing expo and showed it to the KAI scissors people to see if I could get a replacement part or cutter and they just laughed...