Don't know your loppers, but I have a similarly heavy pair and like you say, they're built like a tank. I've put enough pressure on them to have the hickory handles bend slightly, and no apparent harm; I think they're probably heavier than a pro would want to use.

Just the hand grips on mine are wood, no human could bend the handles. I'll try to post a pic later.

Finally got a pic of the loppers. The steel handles are 7/8 X1/4 x18" plus the wood grips. Here goes nut'n trying to get the pic in.

I had a similar pair but the wood covered 1/2 the length of the steel handle.

Amazingly strong. I bought them about 30 yr ago at a garage sale of one of the richest men in Canada for about $6 .

They were stamped DISSTON. I misplaced them, I think it was while I was building a bike trail along the Assinaboine River. I would commit a felony to get them back.

I think about them every time I pick up one of my 5 crappy replacements I am currently using.

The only loppers that are close to as good as those Disstons are the top of the line Felco 36" for about $200