We have certainly discussed handles on this forum before. I was not the only one who suggested that the handles on the Lee Valley chisels were way too fat. And I have mentioned numerous times that traditional handle material was beech and ash and that Roubo mentions hornbeam also.

It is a pretty easy thing to temper a chisel so that it is harder, but most chisels from before 1840 (when there were more serious hand tool workers) were tempered softer than David's chisels. I use these chisels and prefer them. When I had some chisels hardened and less tempered, I had chisels that were more work to sharpen, but did not last any longer in use.